Difference between revisions of "5.6 GHz"
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===24v relay operation=== | ===24v relay operation=== | ||
| − | Most of these relays are often 24v coils - use a switching regulator from ebay as shown | + | Most of these relays are often 24v coils - use a switching regulator from ebay as shown in the above picture. |
Revision as of 18:04, 18 September 2017
Amateur TV activity on the 6 cm band is increasing due to the availability of cheap modules intended to transmit “First Person Video” (FPV) back from drones to their operators.
Frequency choice
The UK amateur band plan is shown on the RSGB website here: https://thersgb.org/services/bandplans/html/rsgb_band_plan_2017.htm
GB3KM has a licensed input on 5665 MHz and this has been chosen as the primary ATV operating frequency.
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.
Equipment=
The FPV units are widely advertised on eBay 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.
Using dish aerials of 30 – 60 cm (such as a surplus Sky dish), line of sight ranges of 80 km can easily be achieved. P5 (noise free) FM ATV pictures have beenexchanged over an 85 km path using the equipment pictured.
Detail of G8GKQ transceiver setup is shown here and as seen at CAT17 - the presentation is available here.
Antennas
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.
It is also possible to use a satellite mini dish with a suitable feed.
Antenna change over relays
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. The surplus SMA relays often available at rallys are ideal for 5.6 GHz. 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.
Reverse SMA
Be aware that the relays are almost certain to be standard SMA connectors and the 5.6GHz FPV units are reverse SMA. Adapters are available on ebay on other suppliers.
24v relay operation
Most of these relays are often 24v coils - use a switching regulator from ebay as shown in the above picture.