Es'hail-2 Basic Information

From BATC Wiki
Jump to: navigation, search

To receive Es'hail-2 at 26°E you can use standard satellite LNBs. These can also be modified. (Note there are other standards and new wideband LNBs. We are talking about traditional ones available in 2019). This is intended to be a basic guide, there are more details and information on how to modify equipment to greatly improve performance is available on this page

Basics

Update on how to align your dish

Now Oscar 100 is "on air" the advice about aligning your dish on BADR4 etc is out dated.

Use some SDR hardware (and £10 RTL dongle will do) and something like the SDRconsole or SDR# programs set for 1MHz bandwidth centered on 739 / 740MHz. Supply 12v to the LNB and look for a bump of around .5MHz bandwidth.

This is the easiest way as there are no other signals in that band, set the elevation to ~ 36 degrees and gently scan across in Azimuth until you see the bump.

You can then use the TV beacon to tweak for maximum signal - the types of MER you should receive depending on dish size are listed on the bottom of this page: https://wiki.batc.org.uk/Receiving_Oscar_100_DATV_signals

Original guide - pre Oscar 100

The original step by step guide to setting up and aligning your dish to receive Es'hail-2 appeared in CQ-TV 261 contains good advice on setting up your dish and the direction of satellite and is available for download here: Getting ready for Es'hail-2

More details on LNBs, including modifying the Octagon units for external lock can be found here: Es'hail-2_LNBs_and_Antennaes

DC Supply

The basic LNB requires a DC supply fed up the coax. This powers the internals and also selects polarisation. A 12V supply selects Vertical polarisation, an 18V supply Horizontal polarisation. Standard LNBs like the Octagon range have two local oscillator (LO) frequencies, 9.75 GHz and 10.6 GHz. The higher is selected by adding a 22kHz signal to the DC supply. For Es'Hail-2 the lower LO is used and this 22kHz tone is not required. Some newer wideband LNBs intended for SkyQ are different, so beware.

The 12V or 18V LNB supply and returned signals share the same coax. A bias-T https://en.wikipedia.org/wiki/Bias_tee is needed to separate the DC from the IF but this can be very simple. Either buy one or make it using an RF choke and a DC blocking capacitor. There are some designs available elsewhere in this Wiki, PCBs in the BATC shop and advice on the BATC forum. It is also possible to use a standard satellite receiver or BATC Minitiouner to provide the DC supply and split out the signals using a power splitter.

Intermediate Frequency

The normal intermediate frequency (IF) is in the range 950 MHz to 2150 MHz. For amateur use we can extend this somewhat from about 500 MHz to about 2.5 GHz with most LNBs. The 9.750 GHz local oscillator is selected by default, which translates the 10.489 MHz EsHail-2 transponder down to 739 MHz. The LO is not especially stable nor accurate, it is adequate for it's intended purpose. For more stability, see the section on reference locking.

The Es'Hail-2 satellite currently has two operational beacons on 10.706 GHz using vertical polarisation and 11.205 GHz using horizontal polarisation that can be used for peaking and setting the polarisation offset. The latter is adjusted by rotating the LNB ~20 degrees to look for a null in the beacon on the opposite polarisation.

The LNB gain is very high, 55dB or more but these are relatively high frequencies so good quality coaxial cable is still needed. The impedance is 75 ohms. Don't be tempted to use very cheap satellite coax as it will pick up interference from local phone base stations etc.

To receive the transponders with a standard LNB you will need a receiver that can tune to 739 MHz. Many software defined radios can do this. Alternatively a frequency converter can be used or, more advanced, the LNB local oscillator can be changed, for example to move the IF up to the 23cm band or down to 70cm.

Dishes

For reception, a dish from about 60cm upwards will work. Note though that a dish this small will not be able to receive the broadcast TV channels from 26E due to interference from adjacent satellites. Typically this needs a 90cm plus dish. However, there are currently no adjacent satellites using 10.5 GHz so this problem will not impact the amateur service transponders. For the uplink, the dish size required depends on how much 2.4 GHz power you can generate and what DATV bandwidth you want to use. A 1.2m dish is likely to be a good compromise for CW, SSB, NBFM and Reduced Bandwidth DATV.

Aligning on the Satellite

Es'Hail-2 is nominally located on the geostationary arc at 26° East. Here [LINK] is a calculator to work out where to point your dish, or use one of the many web pages like this: http://www.satsig.net/maps/satellite-tv-dish-pointing-uk-ireland.htm or https://www.dishpointer.com/ and many others.

Aligning in the UK based on TV signals is difficult as the adjacent signals from Sky 2 degrees to the East are very strong. The easiest method is to use these strong signals, align and peak on Sky and then move the dish an appropriate amount, in the UK typically ~2 degrees to the South and ~0.5 degrees higher in elevation.

For example in London Es'Hail-2 (26°E) is at Azimuth 147.9° and Elevation 26.2° and Astra (28°E) is at Azimuth 145.4° and Elevation: 25.4° so having found Astra, turn the dish 2.5° to the South and increase the elevation by 0.7°. The simplest way to do this is using geometry, so for example if the feed arm is 100cm long it needs to move 100 sin(2.5°) = 4.4cm to the right and 100 sin(0.7°) = 1.2cm up. This approximation will be close enough and generally easier to measure than with a protractor.

The Es'Hail-2 satellite currently has two operational beacons: one on 10.706 GHz using vertiical polarisation and another on 11.205 GHz using horizontal polarisation that can be used for peaking and setting the polarisation offset. The latter is adjusted by rotating the LNB ~20° to look for a null in the beacon on the opposite polarisation. The 10.706 MHz beacon will appear at an IF of 956 MHz and the 11.205 GHz beacon will appear at 1455 MHz, noting with a standard LNB that there may be a significant (100 KHz) frequency error.

Amateur Service

The narrow-band transponder (SSB and CW) will down-link on frequencies 10489.55 MHz to 10489.8 MHz (739.55 MHz - 739.8 MHz on a standard IF) with vertical polarisation (12v on the coax). The wide-band transponder (DATV) will down-link on 10491 MHz to 10499 MHz (741 MHz to 749 MHz standard IF) with horizontal polarisation (18v on the coax).

The narrow-band bandplan can be found here: https://amsat-dl.org/p4-a-nb-transponder-bandplan-and-operating-guidelines

The wide-band bandplan can be found here: images/2/2a/Eshail2_DATV_Bandplan_V1c.pdf

Receiving Oscar 100 DATV signal

A guide to receiving the DATV signals in the wide =band transponder can be found here Receiving Oscar 100 DATV signals