Difference between revisions of "5.6 GHz"

From BATC Wiki
Jump to navigation Jump to search
 
(160 intermediate revisions by 11 users not shown)
Line 1: Line 1:
 +
[[File:5.6 GHz Orientation Small.jpg|300px|center]]
 +
It is very easy (and low cost) to get on the air on 5.6GHz (the 6 cm amateur band), using the cheap modules intended to transmit “First Person Video” (FPV) back from drones to their operators.  These units can be used without any modifications to get on air, and with simple WiFi plate or dish antennas (and a clear line of sight path) can be used to send pictures to stations using the same equipment over paths in excess of 50km.
  
It has just become very easy (and low cost) to get on the air on 5.6GHz (the 6 cm amateur band) using the cheap modules intended to transmit “First Person Video” (FPV) back from drones to their operators.
+
M0KPW has an excellent website describing his 5.6GHz system http://www.5-6ghz-atv.co.uk/
  
These units can be used without any modifications to get on air and with a simple wifi plate or dish antennae and a clear line of sight path be used to can send pictures to stations using the same equipment over 50 Kms away.
+
==Frequency choice==
  
[[File:5.6 GHz Orientation Small.jpg|500px|center]]
+
The overall UK amateur band plan is shown on the RSGB website here: https://rsgb.org/main/operating/band-plans/. As the UK amateur frequency allocation for 5 GHz is not contiguous spectrum, the RSGB has some [https://rsgb.org/main/operating/band-plans/microwaves/5-7-and-10ghz/ useful guidance] which is adapted below with arrow markers:-
 +
  
 +
[[File:bandplan.JPG|800px]]
  
==Frequency choice==
+
GB3KM has a licensed input on 5665 MHz and this has been chosen as the primary ATV operating frequency.  Audio WB-FM operators have been using 5825 and 5840 MHz.  5825 MHz is too close to the band edge for ATV, and 5840 MHz is marginal. So 5665 is the general ATV preference
  
The UK amateur band plan is shown on the RSGB website here: https://thersgb.org/services/bandplans/html/rsgb_band_plan_2017.htm
+
The FPV equipment receive and transmit frequencies are set using DIP switches, and most tune to 5665 MHz – but care needs to be taken when selecting equipment to make sure it does cover this frequency.  Example channel tables are shown at the bottom of this page.
  
GB3KM has a licensed input on 5665 MHz and this has been chosen as the primary ATV operating frequency.
+
==Equipment==
  
The FPV equipment receive and transmit frequencies are set using DIP switches, and most tune to this frequency but care needs to be taken when selecting equipment to make sure it does cover this frequency.
+
The FPV units are widely advertised on eBay and other sites with titles similar to “Tarot 5.8G 600MW Telemetry TX/RX Combo for FPV Image Transmission TL300N” and are available at reasonable prices.  The typical units are very small but have reasonable FM-TV performance with a quoted transmitter spec of 600mW output and receiver sensitivity of -80dBm.  Amplifiers are available to raise the output power to 2 watts or more.
  
==Equipment==
+
[[File:Tairot 1.jpg|400px]]
  
The FPV units are widely advertised on eBay and other sites with titles similar to “Tarot 5.8G 600MW Telemetry TX/RX Combo for FPV Image Transmission TL300N” and are available at reasonable prices.  The typical units are very small but have reasonable FM-TV performance with a quoted spec of 600 milliwatts out and receiver sensitivity of -80 dBm.  Amplifiers are available to raise the output power to 2 watts or more.
+
Be aware – we have found that on some receiver units, the video output is on the Red phono lead and not the expected Yellow lead!
  
[[File:Tairot 1.jpg|400px]]
+
Some other users' stations are described here [[5.6 GHz Equipment Examples]].
  
 
===Mounting the equipment===
 
===Mounting the equipment===
Due to the very high losses in co-ax cable at 5.6GHz it is recommended that you mount the units very close to the antennae and run long 12v DC and Audio and video cables back down the cable to the shack or operating position.   
+
Due to the very high losses in co-ax cable at 5.6GHz it is recommended that you mount the units very close to the antennas and run long 12V dc, audio and video cables back down to the shack or operating position.   
Also whilst these units are very small they do run very hot in operation and it is suggested you provide a good heatsink for both Tx and Rx - mounting them in a diecast box on the back of the antennae is ideal.
 
  
 +
Be aware also, that whilst these units are very small they do run very hot in operation, and it is suggested that you provide a good heatsink for both Tx and Rx – mounting them in a diecast box on the back of their respective antennas is ideal.
  
[[File:20170910 103215 G8GKQ TXCR 6cm AT CAT17.jpg|300px|G8GKQ 6cm Transceiver - .]]
+
[[File:GKQ 5.6v2.JPG|600px]]
  
  
Detail of G8GKQ transceiver setup is shown here (receiver unit on left & transmitter with fan on the right)
+
Details of G8GKQ's transceiver setup is shown here (receiver unit on left & transmitter with fan on the right)
  
 
===Transmit amplifiers===
 
===Transmit amplifiers===
  
Whilst the basic units work very well and have been used to transmit over 60 Kms, power amplifiers to boost the 600mw transmitter signal to 2 - 4 watts are available from several suppliers on ebay and other sites and will significantly increase the distance the units will work over.  These should be connected after the transmit unit but before any antennae change over relay and remember that his will increase the volt drop on any long 12v cable feeding the transmitter at masthead.  
+
Whilst the basic units work very well and have been used to transmit over paths of 60km, power amplifiers to boost the 600mW transmitter signal to 2—4 Watts are available from several suppliers on eBay and other sites, and will significantly increase the path length that the units will work over.  These amplifiers should be connected after the transmit unit, but before any antenna change over relay(s) – and remember that his will increase the volt drop on any long 12V cable feeding the transmitter at the masthead.
 +
 
 +
Be warned!!  Several users have found these PAs to be "fragile", so you should always make sure that the antenna is connected – and all connectors done up tight – before applying dc or RF power.  We are investigating whether they can be made more reliable by reducing the volts / input drive.
 +
 
 +
 
 +
[[File:56PA.jpg|200px]]
  
[[File:56PA.jpg|400px]]
+
==Antenna changeover relays==
  
==Antenna change over relays==
+
The FPV equipment comes as separate Tx and Rx units.  In order to operate on a single antenna, you will need an antenna changeover relay. Note, however, that the losses at 5.6GHz can be significant and care must be taken when wiring up the units to ensure RF cables are of good quality, and kept to a minimum length – semi-rigid cables fitted with SMA connectors are ideal. 
  
The FPV equipment comes as separate Tx and Rx units.  In order to operate on a single aerial, you will need an antennae changeover relay, however the losses at 5.6GHz can be significant and care must be taken when wiring up the units to ensure RF cables are of good quality and kept to a minimum length - semi rigid cable with SMA connectors are ideal.   
+
PL259 and even BNC connectors are very lossy at 5.6GHz and should not be used, but the surplus SMA relays often available at rallys are ideal for 5.6 GHz.   
  
PL259 and even BNC connectors are very lossy at 5.6GHz and should not be used but the surplus SMA relays often available at rallys are ideal for 5.6 GHz.
+
See [[Antennae changeover relays|this wiki page]] for more details on suitable relays, 24 volt operation, and 4 port (or transfer) relays.
  
If no suitable relay is available It may be cheaper to use a separate antenna for receive and transmit as shown in the picture below.
+
If no suitable relay is available, it may be cheaper to use separate antennas for receive and transmit as shown in the picture below – note the Tx and Rx units are mounted directly on the back of the flat panel antennas.
  
[[File:562.jpg|300px]]
+
[[File:562.jpg|200px]]
  
 
===Reverse SMA===  
 
===Reverse SMA===  
  
Be aware that all the 5.6GHz FPV units are reverse SMA (like wifi equipment) and all low loss cables, unless bought specifically for the purpose, and suplus SMA relays are almost certain to be standard SMA connectors and will not fit.  Adapters from reverse to standard SMA are available on ebay or other suppliers.
+
Be aware that all the 5.6GHz FPV units use "reverse SMA" connectors (as used on WiFi equipment) and that all low-loss cables (unless bought specifically for the purpose) and surplus SMA relays will almost certainly have standard SMA connectors – which will not fit.  Adapters from reverse to standard SMA are available on eBay or other suppliers – search for "RP-SMA to SMA adaptor" or similar wording.
 +
 
 +
==Antennas==
 +
 
 +
As 5.8GHz is used by broadband wireless networks, there is a wide choice of antennas available for use on 5.6GHz ATV.  These can range from flat plates/panels to wire mesh (grid) dishes, as seen in the above pictures.
 +
 
 +
 
 +
Horizontal polarisation has been chosen as the standard (waveguide feeds needs to have the long dimension of the aperture – and/or horn – vertically oriented when feeding dishes)
 +
 
 +
=== Satellite dishes ===
 +
 
 +
It is also possible to use a satellite mini dish with a suitable feed, such as a waveguide/horn to the design by G4NNS – see here for construction details: http://myweb.tiscali.co.uk/g4nns/FeedHorn.html
 +
 
 +
The picture shows a Sky mini dish fed with a WA5VJB log-periodic PCB feed http://www.wa5vjb.com/products1.html – these are available in the UK from G4DDK. http://www.g4ddk.com/Prices2.html
 +
 
 +
Dishes of this size typically have a beam width of 4—8 degrees.
 +
 
 +
[[File:56 dish feed.JPG|400px]]
 +
 
 +
 
 +
M1BKF found a very interesting 5.6GHz feed for standard f/d ratio satellite dishes; it contains what looks like a PCB yagi, and was available from www.antennas-amplifiers.com:
 +
 
 +
[[File:PCB dish feed.JPG|200px]]                [[File:PCB dish feed2.JPG|300px]]
 +
 
 +
=== DIY BiQuad antennae ===
 +
 
 +
This web page http://buildyourownantenna.blogspot.co.uk/2014/07/double-biquad-sector-antenna-for-5-ghz-wifi.html has a well engineered double BiQuad antenna with a quoted 13dBi gain.
 +
 
 +
Note in the picture G8JAN has directly connected the Tx module to the antenna to avoid co-ax losses.
 +
 
 +
[[File:feed.jpg|400px]]
 +
 
 +
==Video equipment - Rx==
 +
The receiver output will need to be directly connected to a monitor with a composite video input to view the received the signal – normally on a yellow phono or RCA connector. 
 +
 
 +
===Video squelch defeat===
 +
 
 +
Beware of using modern flat-screen monitors which have a video squelch – these will not display noisy signals, and just give a blue screen until they get a strong video signal.
 +
 
 +
There are a number of circuits around to defeat the squelch and also improve the readability of the signal.
 +
 
 +
===Syncsmurf by PE1RQM===
 +
– kits are available; details on the [https://translate.google.com/translate?hl=auto&sl=auto&tl=en-US&u=https%3A%2F%2Fwww.pe1rqm.nl%2Fsyncsmurf2%2F webpage here].
 +
 
 +
[[File:syncsmurf1.jpg|200px]]
 +
 
 +
Results are very impressive:
 +
 
 +
[[File:syncsmurf2.jpg|400px]]
 +
 
 +
===eachine FPV recorder===
 +
 
 +
Several people have reported that they are using these devices, available from various sites, and as well as defeating the monitor blue screen by inserting syncs on noise they have a single push button record facility.  They record to an SD card which can be removed and the files viewed on a PC; users report that you need to use a good quality SD card, and that they have had problems with Kingston branded cards – Sandisk are preferred.
 +
The one issue with them is that they crop PAL signals removing 15% at the top and bottom of the picture. This is a hardware issue, so no amount of software updates will solve it. The workaround is that the unit will not crop PAL pictures if the video input is present when the unit is powered up. NTSC pictures are not affected
 +
 
 +
[[File:emachine dvr.JPG|300px]]
 +
 
 +
===Video sync processor===
 +
 
 +
[[File:cqtv 129.jpg|300px]]
 +
 
 +
 
 +
Or any video sync processor may be usable such as the Advanced Converter Enhancer used by many stations on 23cms FM TV transmissions.
 +
 
 +
[[File:ACE.jpg|300px]]
 +
 
 +
==Receive Pre-amplifiers==
 +
 
 +
The basic drone recievers are fairly sensitive.  However the perfomance can be improved by using a pre-amp before the unit but is also recommended that a bandpass filter included on the pre-amp output.
 +
 
 +
A cheap but high performance pre-amp can be made using the surplus LNA PCBs available from Franco in Italy https://www.rf-microwave.com/en/nbp/nmp/10-ghz-amplifier-24ghz-doubler/su-02/ 
 +
 
 +
These boards are fantastic value for money and can be used to make 10GHz pre-amps or the devices can be used to replace blown devices in most DB6NT transverters.
 +
 
 +
The following document shows the simple mods required to make a 5.6GHz pre-amp: 
 +
 
 +
[[File:5.6GHz pre-amp.JPG|600px]]
 +
 
 +
The unit requires 5volts and minus volts for bias which can either be generated using the circuit on the main Franco PCB or the following circuit:
 +
 
 +
[[File:supply.jpg|600px]]
 +
 
 +
==Video equipment - Tx==
 +
An old camcorder with a yellow phono "video out" socket is an ideal video and audio source for the transmitter.
 +
 
 +
Don't forget that you will need to display your call sign to remain legal.  This can be a video generator, a .jpg card reader with video out, or a piece of card with your call sign scribbled on it!
 +
 
 +
===Media card reader===
 +
 
 +
A simple way to generate test patterns is to use a media card reader loaded with .jpg files – these are available on several sites, just search for "SD card media AV player" – but make sure you get one which outputs PAL video.
 +
 
 +
[[File:av player.JPG|200px]]
 +
 
 +
===PicDream===
 +
The PicDream project uses a single PIC chip and a 4MHz crystal to generate a black and white test pattern – simple but effective – the original project was described in CQ-TV 180 and re-printed in CQ-TV 247.
  
===24v relay operation===
+
[[File:Picdream 247.JPG|400px]]
  
Most of the surplus SMA relays are often 24v coils - use a switching regulator from ebay as shown in the picture (search for step up buck regulator) to boost the 12volts on transmit to 24v.
+
The PIC code is available for download here: batc.org.uk/cq-tv/software/picdream.zip
  
[[File:reg.JPG|300px]]
+
===PicDream II===
  
==Antennas==
+
[[File:picdream2.jpg|400px]]
 +
 
 +
 
 +
The PicDream II project uses a PIC chip and an AD724 PAL ecnoder chip to generate a colour test pattern with moving insets. The text and colours on the test pattern can be set through it's serial link.
 +
 
 +
Further information is at https://github.com/F1CJN/PICDREAM-II
 +
 
 +
===Raspberry Pi - PA3CHM image generator===
  
As 5.8GHz is also used by broadband wireless networks, there is a wide choice of antennae available for use on 5.6GHz ATV.  This can range from flat plates to wire mesh dishes as seen in the above pictures.
+
CQ-TV 247 published details of a simple RPi-based test card generator by Ernest PA3CHM.
  
It is also possible to use a satellite mini dish with a suitable feed such as a wave guide horn to the design by G4NNS - the picture shows a Sky mini dish fed with a WA5VJB log period PCB feed (available from G4DDK).
+
[[File:PA3chm.JPG|400px]]
  
[[File:G8GTZ 5.6.JPG|300px]]
+
Full details are on his website: http://www.pa3hcm.nl/?p=248
  
==Video equipment==
+
===Raspberry Pi - Portsdown patterns===
 +
The BATC Portsdown project can be configured to deliver composite video and audio out from the RPi multi-jack plug. 
  
===Rx===
+
[[File:GKQ July 2017 (Small).JPG|400px]]
The receiver will need to be directly connected to a composite video input monitor to view the received the signal - normally on a yellow phono or RCA connector. Beware of using modern flat screen monitors which have a video squelch which will not display noisy signals and just give a blue screen until they get a strong video signal. 
 
  
There are a number of circuits around to defeat the squelch.
+
This can be test patterns, RPi desktop, or the Portsdown camera and microphone – [[Analog Video Output|see this wiki page for more details]] making the RPi the only piece of video/audio equipment you need to drive the 5.6GHz transmitter.
  
===Tx===
+
===Stand alone Raspberry Pi animated test card generator===
An old camcorder with a yellow phono video out socket is an ideal video and audio source for the transmitter but don't forget you will need to display your call sign to remain legal.  This can be a video generator, a jpeg card reader with video out, the Portsdown system with video out or a piece of card with your call sign scribbled on it!
+
This is the stand alone version of the animated test card generator that is part of the Portsdown software 
 +
[[RPi Test Card| - <u>see this wiki page for more details</u>]]
  
 
==On the air==
 
==On the air==
  
Using dish aerials of 30 – 60 cm line of sight ranges of 80 km can easily be achieved.   
+
Using dish aerials of 30&mdash;60cm, line of sight ranges of 80km can easily be achieved.   
  
P5 (noise free) FM ATV pictures have been exchanged over an 138km path using the equipment described on this page - the picture below shows G4CPE/p being received over a slightly obstructed 66Km path.
+
P5 (noise free) FM ATV pictures have been exchanged over a 138km path using the equipment described on this page &ndash; the picture below shows G4CPE/P on Dunstable Downs being received at the Ridgeway, near Didcot, over a slightly obstructed 66km path.
  
 
[[File:CPE 5.6GHz.JPG|400px]]
 
[[File:CPE 5.6GHz.JPG|400px]]
  
  
Horizontal polarity has been chosen as the standard and dishes typically have a beam width of 4-8 degrees.
+
Dunkery Beacon near Minehead, to Cleeve Common near Cheltenham.
 +
The picture shows G8GTZ/P received by G8GKQ/P over the 138km path.
 +
 
 +
[[File:snap5 small.jpg|400px]]
 +
 
 +
 
 +
2018-04-21: The UK "record" for a contact using standard FPV units was increased to 153km between GW3NWR/P at Bylchau, North Wales to M0KPW/P and G0HIK/P at the Kirkstone Pass Inn, Cumbria.
 +
 
 +
This has since been surpassed.
 +
 
 +
==FM voice only==
 +
 
 +
Several stations in the Gloucester and Bolton area are using these units for wideband FM voice only.  This is achieved by simply putting high level (1V peak-peak) audio on the yellow video TX phono input &ndash; this modulates the main high level carrier with audio rather than video (the two audio phono connectors &ndash; red and white &ndash; can be ignored). On RX, the yellow phono connector of the receiver is simply connected to a line level input of an audio amplifier. 
 +
 
 +
It is done this way because the two audio subcarriers transmitted by the unit are at a level 20dB lower than that of the main (video)carrier. However, as it is using the same bandwidth Rx and Tx system, performance will be no better than FM video &ndash; ideally the 480MHz RX IF would be tapped off in to an SDR or narrow band receiver to give significantly enhanced (+20db?) narrow band performance.
  
 
==Activity hot spots==
 
==Activity hot spots==
  
Know users include:
+
There is a Google map showing approximate locations of stations thought to be active on 5.6GHz FM &ndash; if you are on 5.6GHz, you can add or edit your station: https://www.google.com/maps/d/u/0/edit?mid=1e4keFSFWy6wLUQNF3IT3n6h90eU&ll=52.39133141509076%2C-1.8917942000000494&z=7
 +
 
 +
Known users include:
  
* Southern England = G8GKQ, G8GTZ, G0UHY, G8XZD, G4UVZ, G3VPF
+
*Southern England = G8GKQ, G8GTZ, G0UHY, G8XZD, G4UVZ, G3VPF
* Dunstable area = M0SKM, G4CPE, G0WFT
+
*Dunstable area = M0SKM, G4CPE, G0WFT
* North-east = GB3KM, G1LPS, M0DTS
+
*North-East = GB3KM, G1LPS, M0DTS
 
*Cheltenham = G0LGS, M0RKX and G4NZV (using WB audio only)
 
*Cheltenham = G0LGS, M0RKX and G4NZV (using WB audio only)
*Bolton Wireless Club =  G4JLG, M0UFC, MW1FGQ, G6GVI (PW “Siren” Article)
+
*Bolton Wireless Club =  G4JLG, G6GVI, G8PEF, M0UFC, MW1FGQ (PW “Siren” Article)
*Hereford = G8XYJ
+
*Ludlow, Shropshire = G8XYJ
 
*Yorkshire = G8BYN
 
*Yorkshire = G8BYN
*Norfolk = G4NJJ, G8AJN and M1BKF
+
*Norfolk = G4NJJ, G8JAN, G4WVU and M1BKF
*Cumbria - Barrow in Furness radio Club project
+
*Cumbria - Barrow-in-Furness Radio Club project
 +
*Merseyside - G3NWR
 +
*Northern Ireland = GI4DOH, GI3VAF, GI0GDP, GI7UGV
  
 
[[File:cpe2.jpg|400px]]
 
[[File:cpe2.jpg|400px]]
Line 104: Line 233:
 
==More information==
 
==More information==
  
Dave G8GKQ did a presentation at the BATC annual convention CAT17 in September 2017 on getting started on 5.6 GHz ATV.
+
Dave G8GKQ did a presentation at the BATC annual convention CAT17 in September 2017 on getting started on 5.6GHz ATV.
*The presentation is available here https://wiki.batc.tv/images/9/94/CAT17_Portsdown_Update.pdf
+
*The presentation is available here https://wiki.batc.org.uk/images/4/42/CAT17_5.6_GHzv2.pdf
*The video of the session is available on the BATC youtube channel here https://www.youtube.com/watch?v=XJzGNsGmE9Y
+
*The video of the session is available on the BATC YouTube channel here https://www.youtube.com/watch?v=XJzGNsGmE9Y
 +
 
 +
==On line support / social media==
 +
 
 +
There is a thread running on the BATC forum where the ATV community are exchanging ideas and also posting results of the latest on air tests.  https://forum.batc.org.uk/viewtopic.php?f=2&t=5026
 +
 
 +
Note that the BATC core team do not regularly visit Facebook pages - time is just too short to monitor everything and it's not easy to follow threads on Facebook.
 +
 
 +
==Technical information==
 +
 
 +
===SM201R===
 +
The large RX chip in most units has had the part number removed, however it appears that a lot of receivers use the SM201R module.  The spec and pinout are shown below but notice the frequency range of this particular unit does not seem to cover 5665MHz, so make sure the one you buy does!
 +
 
 +
[[File:sm201r 2.jpg|500px]]  [[File:sm201r 3.JPG|200px]]
 +
 
 +
 
 +
[[File:sm201r 1.JPG|500px]]
 +
 
 +
===S meter output===
 +
 
 +
Looking at the above table, it appears that the RSSI is available on pin 17 of the SM201R and could potentially be used for a signal strength meter to help align the antennas when setting up a QSO.
 +
 
 +
It also appears that the SM201R uses a 480MHz IF (same as the Comtech) and potentially could be modified with narrower filters to improve RF performance.
 +
 
 +
====Tx and Rx perfomance====
 +
 
 +
Initial measurements suggest the TX bandwidth is 25&mdash;30MHz.
 +
 
 +
[[File:5.6GHz spectrum.jpg|500px]]
 +
 
 +
This accounts for the quoted RX sensitivity at -80dBm which may be improved by an LNA but will ultimately be limited by the RX IF bandwidth.
 +
 
 +
===Channel Listings===
 +
 
 +
As mentioned above, the channel settings vary from manufacturer to manufacturer.  This table is taken from the Tarot data sheet which uses the SM201R module but does include 5665MHz:
 +
 
 +
[[File:Tarot_Channels.jpg|603px]]
 +
 
 +
And this is the table for the Eachine TS835 transmitter:
 +
 
 +
[[File:Channels_2.jpg|619px]]
 +
 
 +
This table is from a "Fat Shark" transmitter that does not cover 5665 MHz:
 +
 
 +
[[File:Fat_Shark.PNG|300px]]
 +
 
 +
==Improvements to Commercial Units==
  
There is a thread running on the BATC forum where the ATV community are exchanging ideas and also posting results of the latest on air testshttp://www.batc.org.uk/forum/viewtopic.php?f=2&t=5026
+
In CQ-TV 260, Achille I2GLI described improvements and additions to the Mateksys VTX-HV drone transmitter to make a high quality 18 watt output 5.6 GHz FM transmitter.  One of the improvements was to replace the video and sound baseband circuitry.  The published circuit diagram in online CQ-TV was a little unclear (although the printed version is good)The circuit diagram is reproduced below.
 +
[[File:BandaBase.jpg|672px]]

Latest revision as of 10:36, 27 February 2022

5.6 GHz Orientation Small.jpg

It is very easy (and low cost) to get on the air on 5.6GHz (the 6 cm amateur band), using the cheap modules intended to transmit “First Person Video” (FPV) back from drones to their operators. These units can be used without any modifications to get on air, and with simple WiFi plate or dish antennas (and a clear line of sight path) can be used to send pictures to stations using the same equipment over paths in excess of 50km.

M0KPW has an excellent website describing his 5.6GHz system http://www.5-6ghz-atv.co.uk/

Frequency choice

The overall UK amateur band plan is shown on the RSGB website here: https://rsgb.org/main/operating/band-plans/. As the UK amateur frequency allocation for 5 GHz is not contiguous spectrum, the RSGB has some useful guidance which is adapted below with arrow markers:-


Bandplan.JPG

GB3KM has a licensed input on 5665 MHz and this has been chosen as the primary ATV operating frequency. Audio WB-FM operators have been using 5825 and 5840 MHz. 5825 MHz is too close to the band edge for ATV, and 5840 MHz is marginal. So 5665 is the general ATV preference

The FPV equipment receive and transmit frequencies are set using DIP switches, and most tune to 5665 MHz – but care needs to be taken when selecting equipment to make sure it does cover this frequency. Example channel tables are shown at the bottom of this page.

Equipment

The FPV units are widely advertised on eBay and other sites with titles similar to “Tarot 5.8G 600MW Telemetry TX/RX Combo for FPV Image Transmission TL300N” and are available at reasonable prices. The typical units are very small but have reasonable FM-TV performance with a quoted transmitter spec of 600mW output and receiver sensitivity of -80dBm. Amplifiers are available to raise the output power to 2 watts or more.

Tairot 1.jpg

Be aware – we have found that on some receiver units, the video output is on the Red phono lead and not the expected Yellow lead!

Some other users' stations are described here 5.6 GHz Equipment Examples.

Mounting the equipment

Due to the very high losses in co-ax cable at 5.6GHz it is recommended that you mount the units very close to the antennas and run long 12V dc, audio and video cables back down to the shack or operating position.

Be aware also, that whilst these units are very small they do run very hot in operation, and it is suggested that you provide a good heatsink for both Tx and Rx – mounting them in a diecast box on the back of their respective antennas is ideal.

GKQ 5.6v2.JPG


Details of G8GKQ's transceiver setup is shown here (receiver unit on left & transmitter with fan on the right)

Transmit amplifiers

Whilst the basic units work very well and have been used to transmit over paths of 60km, power amplifiers to boost the 600mW transmitter signal to 2—4 Watts are available from several suppliers on eBay and other sites, and will significantly increase the path length that the units will work over. These amplifiers should be connected after the transmit unit, but before any antenna change over relay(s) – and remember that his will increase the volt drop on any long 12V cable feeding the transmitter at the masthead.

Be warned!!  Several users have found these PAs to be "fragile", so you should always make sure that the antenna is connected – and all connectors done up tight – before applying dc or RF power.  We are investigating whether they can be made more reliable by reducing the volts / input drive.


56PA.jpg

Antenna changeover relays

The FPV equipment comes as separate Tx and Rx units. In order to operate on a single antenna, you will need an antenna changeover relay. Note, however, that the losses at 5.6GHz can be significant and care must be taken when wiring up the units to ensure RF cables are of good quality, and kept to a minimum length – semi-rigid cables fitted with SMA connectors are ideal.

PL259 and even BNC connectors are very lossy at 5.6GHz and should not be used, but the surplus SMA relays often available at rallys are ideal for 5.6 GHz.

See this wiki page for more details on suitable relays, 24 volt operation, and 4 port (or transfer) relays.

If no suitable relay is available, it may be cheaper to use separate antennas for receive and transmit as shown in the picture below – note the Tx and Rx units are mounted directly on the back of the flat panel antennas.

562.jpg

Reverse SMA

Be aware that all the 5.6GHz FPV units use "reverse SMA" connectors (as used on WiFi equipment) and that all low-loss cables (unless bought specifically for the purpose) and surplus SMA relays will almost certainly have standard SMA connectors – which will not fit. Adapters from reverse to standard SMA are available on eBay or other suppliers – search for "RP-SMA to SMA adaptor" or similar wording.

Antennas

As 5.8GHz is used by broadband wireless networks, there is a wide choice of antennas available for use on 5.6GHz ATV. These can range from flat plates/panels to wire mesh (grid) dishes, as seen in the above pictures.


Horizontal polarisation has been chosen as the standard (waveguide feeds needs to have the long dimension of the aperture – and/or horn – vertically oriented when feeding dishes)

Satellite dishes

It is also possible to use a satellite mini dish with a suitable feed, such as a waveguide/horn to the design by G4NNS – see here for construction details: http://myweb.tiscali.co.uk/g4nns/FeedHorn.html

The picture shows a Sky mini dish fed with a WA5VJB log-periodic PCB feed http://www.wa5vjb.com/products1.html – these are available in the UK from G4DDK. http://www.g4ddk.com/Prices2.html

Dishes of this size typically have a beam width of 4—8 degrees.

56 dish feed.JPG


M1BKF found a very interesting 5.6GHz feed for standard f/d ratio satellite dishes; it contains what looks like a PCB yagi, and was available from www.antennas-amplifiers.com:

PCB dish feed.JPG PCB dish feed2.JPG

DIY BiQuad antennae

This web page http://buildyourownantenna.blogspot.co.uk/2014/07/double-biquad-sector-antenna-for-5-ghz-wifi.html has a well engineered double BiQuad antenna with a quoted 13dBi gain.

Note in the picture G8JAN has directly connected the Tx module to the antenna to avoid co-ax losses.

Feed.jpg

Video equipment - Rx

The receiver output will need to be directly connected to a monitor with a composite video input to view the received the signal – normally on a yellow phono or RCA connector.

Video squelch defeat

Beware of using modern flat-screen monitors which have a video squelch – these will not display noisy signals, and just give a blue screen until they get a strong video signal.

There are a number of circuits around to defeat the squelch and also improve the readability of the signal.

Syncsmurf by PE1RQM

– kits are available; details on the webpage here.

Syncsmurf1.jpg

Results are very impressive:

Syncsmurf2.jpg

eachine FPV recorder

Several people have reported that they are using these devices, available from various sites, and as well as defeating the monitor blue screen by inserting syncs on noise they have a single push button record facility. They record to an SD card which can be removed and the files viewed on a PC; users report that you need to use a good quality SD card, and that they have had problems with Kingston branded cards – Sandisk are preferred. The one issue with them is that they crop PAL signals removing 15% at the top and bottom of the picture. This is a hardware issue, so no amount of software updates will solve it. The workaround is that the unit will not crop PAL pictures if the video input is present when the unit is powered up. NTSC pictures are not affected

Emachine dvr.JPG

Video sync processor

Cqtv 129.jpg


Or any video sync processor may be usable such as the Advanced Converter Enhancer used by many stations on 23cms FM TV transmissions.

ACE.jpg

Receive Pre-amplifiers

The basic drone recievers are fairly sensitive. However the perfomance can be improved by using a pre-amp before the unit but is also recommended that a bandpass filter included on the pre-amp output.

A cheap but high performance pre-amp can be made using the surplus LNA PCBs available from Franco in Italy https://www.rf-microwave.com/en/nbp/nmp/10-ghz-amplifier-24ghz-doubler/su-02/

These boards are fantastic value for money and can be used to make 10GHz pre-amps or the devices can be used to replace blown devices in most DB6NT transverters.

The following document shows the simple mods required to make a 5.6GHz pre-amp:

5.6GHz pre-amp.JPG

The unit requires 5volts and minus volts for bias which can either be generated using the circuit on the main Franco PCB or the following circuit:

Supply.jpg

Video equipment - Tx

An old camcorder with a yellow phono "video out" socket is an ideal video and audio source for the transmitter.

Don't forget that you will need to display your call sign to remain legal. This can be a video generator, a .jpg card reader with video out, or a piece of card with your call sign scribbled on it!

Media card reader

A simple way to generate test patterns is to use a media card reader loaded with .jpg files – these are available on several sites, just search for "SD card media AV player" – but make sure you get one which outputs PAL video.

Av player.JPG

PicDream

The PicDream project uses a single PIC chip and a 4MHz crystal to generate a black and white test pattern – simple but effective – the original project was described in CQ-TV 180 and re-printed in CQ-TV 247.

Picdream 247.JPG

The PIC code is available for download here: batc.org.uk/cq-tv/software/picdream.zip

PicDream II

Picdream2.jpg


The PicDream II project uses a PIC chip and an AD724 PAL ecnoder chip to generate a colour test pattern with moving insets. The text and colours on the test pattern can be set through it's serial link.

Further information is at https://github.com/F1CJN/PICDREAM-II

Raspberry Pi - PA3CHM image generator

CQ-TV 247 published details of a simple RPi-based test card generator by Ernest PA3CHM.

PA3chm.JPG

Full details are on his website: http://www.pa3hcm.nl/?p=248

Raspberry Pi - Portsdown patterns

The BATC Portsdown project can be configured to deliver composite video and audio out from the RPi multi-jack plug.

GKQ July 2017 (Small).JPG

This can be test patterns, RPi desktop, or the Portsdown camera and microphone – see this wiki page for more details making the RPi the only piece of video/audio equipment you need to drive the 5.6GHz transmitter.

Stand alone Raspberry Pi animated test card generator

This is the stand alone version of the animated test card generator that is part of the Portsdown software - see this wiki page for more details

On the air

Using dish aerials of 30—60cm, line of sight ranges of 80km can easily be achieved.

P5 (noise free) FM ATV pictures have been exchanged over a 138km path using the equipment described on this page – the picture below shows G4CPE/P on Dunstable Downs being received at the Ridgeway, near Didcot, over a slightly obstructed 66km path.

CPE 5.6GHz.JPG


Dunkery Beacon near Minehead, to Cleeve Common near Cheltenham. The picture shows G8GTZ/P received by G8GKQ/P over the 138km path.

Snap5 small.jpg


2018-04-21: The UK "record" for a contact using standard FPV units was increased to 153km between GW3NWR/P at Bylchau, North Wales to M0KPW/P and G0HIK/P at the Kirkstone Pass Inn, Cumbria.

This has since been surpassed.

FM voice only

Several stations in the Gloucester and Bolton area are using these units for wideband FM voice only. This is achieved by simply putting high level (1V peak-peak) audio on the yellow video TX phono input – this modulates the main high level carrier with audio rather than video (the two audio phono connectors – red and white – can be ignored). On RX, the yellow phono connector of the receiver is simply connected to a line level input of an audio amplifier.

It is done this way because the two audio subcarriers transmitted by the unit are at a level 20dB lower than that of the main (video)carrier. However, as it is using the same bandwidth Rx and Tx system, performance will be no better than FM video – ideally the 480MHz RX IF would be tapped off in to an SDR or narrow band receiver to give significantly enhanced (+20db?) narrow band performance.

Activity hot spots

There is a Google map showing approximate locations of stations thought to be active on 5.6GHz FM – if you are on 5.6GHz, you can add or edit your station: https://www.google.com/maps/d/u/0/edit?mid=1e4keFSFWy6wLUQNF3IT3n6h90eU&ll=52.39133141509076%2C-1.8917942000000494&z=7

Known users include:

  • Southern England = G8GKQ, G8GTZ, G0UHY, G8XZD, G4UVZ, G3VPF
  • Dunstable area = M0SKM, G4CPE, G0WFT
  • North-East = GB3KM, G1LPS, M0DTS
  • Cheltenham = G0LGS, M0RKX and G4NZV (using WB audio only)
  • Bolton Wireless Club = G4JLG, G6GVI, G8PEF, M0UFC, MW1FGQ (PW “Siren” Article)
  • Ludlow, Shropshire = G8XYJ
  • Yorkshire = G8BYN
  • Norfolk = G4NJJ, G8JAN, G4WVU and M1BKF
  • Cumbria - Barrow-in-Furness Radio Club project
  • Merseyside - G3NWR
  • Northern Ireland = GI4DOH, GI3VAF, GI0GDP, GI7UGV

Cpe2.jpg

More information

Dave G8GKQ did a presentation at the BATC annual convention CAT17 in September 2017 on getting started on 5.6GHz ATV.

On line support / social media

There is a thread running on the BATC forum where the ATV community are exchanging ideas and also posting results of the latest on air tests. https://forum.batc.org.uk/viewtopic.php?f=2&t=5026

Note that the BATC core team do not regularly visit Facebook pages - time is just too short to monitor everything and it's not easy to follow threads on Facebook.

Technical information

SM201R

The large RX chip in most units has had the part number removed, however it appears that a lot of receivers use the SM201R module. The spec and pinout are shown below but notice the frequency range of this particular unit does not seem to cover 5665MHz, so make sure the one you buy does!

Sm201r 2.jpg Sm201r 3.JPG


Sm201r 1.JPG

S meter output

Looking at the above table, it appears that the RSSI is available on pin 17 of the SM201R and could potentially be used for a signal strength meter to help align the antennas when setting up a QSO.

It also appears that the SM201R uses a 480MHz IF (same as the Comtech) and potentially could be modified with narrower filters to improve RF performance.

Tx and Rx perfomance

Initial measurements suggest the TX bandwidth is 25—30MHz.

5.6GHz spectrum.jpg

This accounts for the quoted RX sensitivity at -80dBm which may be improved by an LNA but will ultimately be limited by the RX IF bandwidth.

Channel Listings

As mentioned above, the channel settings vary from manufacturer to manufacturer. This table is taken from the Tarot data sheet which uses the SM201R module but does include 5665MHz:

Tarot Channels.jpg

And this is the table for the Eachine TS835 transmitter:

Channels 2.jpg

This table is from a "Fat Shark" transmitter that does not cover 5665 MHz:

Fat Shark.PNG

Improvements to Commercial Units

In CQ-TV 260, Achille I2GLI described improvements and additions to the Mateksys VTX-HV drone transmitter to make a high quality 18 watt output 5.6 GHz FM transmitter. One of the improvements was to replace the video and sound baseband circuitry. The published circuit diagram in online CQ-TV was a little unclear (although the printed version is good). The circuit diagram is reproduced below. BandaBase.jpg