Posts by GM3SBC

Hello All,

I have enclosed a few photos showing what I have been using over the last several days. Thanks to the many stations that made contact with me on the EsHail 2 Satellite.

The system basically comprises of the following:-

A 1 Metre dish,

Uplink / Downlink feed : 2.4 GHz Helix , 10 GHz Dual mode horn. This is a combined unit.

Power Amplifier, Home design: 2 Watts input 25 Watts Output, driven at approximately 8 Watts output for this application.

10 GHz Home design LNA / Mixer/ I.F. - LO chain 8089.5 MHz driven by 10 MHz GPS Locked.

432 to 2400 Transverter, 10 MHz GPS Locked.

The prime driver was the Scottie Globemaster SDR at a 432 MHz Intermediate Frequency. ( Fitted with the ‘ Scottie Drift Zapper ‘ option providing LO Stability of 0.007 ppm ). (Please see my QRZ.com and Globemaster Groups I.O. for details if you are interested. ).

I have included some photos.

Regards

Ed GM3SBC

Hello, Can I just say a few words about setting a microwave system to receive a remote RF source.

1) First of all FORGET about finding your Satellite.

You must do a System Calibration process first.

You have a dish, . . . . yes. It has a specification , . . . . . . . yes.

FORGET it. It is potentially very wrong.

2) You must do a BORESIGHT calibration of your dish. ? ? . . Ok, you think that your dish is 26 degrees offset angle. . . . WRONG. But what can you do to check it ? Well you need a very reliable signal source of known position. Ah, what if we were to use the SUN as the signal source? Is that not the most accurate source we have. YES, so first of all attach an Azimuth Indicator to your Dish structure reading in degrees. For elevation, have an electronic spirit level to measure the elevation angle of the dish. NOW, here comes the magic to do your dish boresight calibration. At a particular time of day measure your Sun Noise at its peak. Now note immediately YOUR Az and El measurements. Using astronomical tables, compare your readings with the ACTUAL values for you position on this Earth at the particular time of your measurement. NOW calculate the OFFSET ERRORS IN BOTH AZ and EL. Now record these values. SO, you now have your boresight Az and El errors for your dish. You now have the calibration offsets to apply to your dish to ensure your pointing accuracy is high. NOW, before we leave using the Sun as a SIGNAL SOURCE, What is your SUN NOISE ? We must check this to confirm that your receive system is working to the expected performance level for you particular configuration. OK, go check and see what it should really be with an efficient system. There are many software programs available to check. IF you get a low Sun Noise , then you must address your front end design. MATCH, SPILLOVER, ETC, ETC. Whatever you have to do, get close to the theoretical performance.

SO, now you have a credible receive performance, AND you can now calibrate the dish for boresight errors.

NOW, for the first time we think about finding a satellite !

It's easy now. You now have a receive performance that is close perfection, AND you can remove your boresight errors. AH, for the first time you will be able to point exactly at the satellite.

Success at last !

PS, you can have errors of several degrees in boresight with respect to the manfacturers values. My dish has a 4 degree error in Azimuth, Hmm, the beam width is 1.8 degrees. Its a no brainer ! Go calibrate your dish boresight !

Cheers

Ed GM3SBC