linear transponder inverting ssb/cw

[KB3TQO]

im wanting to try different sats and i dont unerstand linear transponder inverting ssb/cw.Fo-29 for example, how do you tx and rx? is it only cw or can you use phone voice?
Please help
thanks

 

[Captain Kilowatt]

FO-29 (Fuji-Oscar-29) is an SSB/CW satellite only. it is not for FM use. A linear transponder type satellite means it does not have any specific one input/output frequency and as long as you are transmitting inside the passband it will repeat your signal out.

Most analog satellites have linear transponders. Linear transponders cover a continuous passband of frequencies for the uplink and downlink. Inverting transponders will invert both the sideband and track frequency in opposing directions (an increase in uplink frequency results in a corresponding decrease in downlink frequency). Since Continuous Wave (CW) is just a carrier, there is no sideband to invert, but frequency does track in the opposite direction. Non-inverting transponders maintain the same sideband for uplink and downlink and track frequency in the same direction.


Please make sure you know what type of satellite you are attempting to work through and NEVER transmit an FM signal through a satellite that has a linear transponder. The best rule is if you can't hear the satellite then do NOT transmit.


AMSAT - Satellite Status

 

[Wire Weasel]

Well what do I do if a satellite is running an extravariant euclidean inverse reanimentensular field, one that ordinarily randomizes phaser beams? What do I do THEN ??

 

[Captain Kilowatt]

Well what do I do if a satellite is running an extravariant euclidean inverse reanimentensular field, one that ordinarily randomizes phaser beams? What do I do THEN ??

Call the manufacturer for warranty work. The spacial injector detector reflector connector is obviously bad.

 

[Wire Weasel]

Call the manufacturer for warranty work. The spacial injector detector reflector connector is obviously bad.

Dammit man I hate it when that happens

 

[KB3TQO]

O.K. On a low elevation pass of Fo-29 I found a QSO on 435.845 upperside band using an indoor j-pole. Am I understanding correctly by assuming that the uplink was on lowerside band? And what was the uplink freq?
Sorry for being ignorant but im having a hard time getting my head around this.
Thanks

 

[Qwazyone]

O.K. On a low elevation pass of Fo-29 I found a QSO on 435.845 upperside band using an indoor j-pole. Am I understanding correctly by assuming that the uplink was on lowerside band? And what was the uplink freq?
Sorry for being ignorant but im having a hard time getting my head around this.
Thanks

Yes, it would have been a LSB transmit on the uplink of about 145.955 at the sat assuming that it was low enough for you to have little or no doppler affect. Now if the op is at AOS on a high pass, the op could be TXing at about 145.952, and at LOS it may be around 145.958.

There is a simple way to figure it out on the linears birds, you add the low uplink freq to the high downlink freq and it will give you somewhat of a majic number. FO-29 is 581.8, AO-7 is 578.1, and VO-52 is 581.15. So if you find a downlink at max elevation for you(LCA) subtract the downlink freq from the number for the sat and you will find the uplink freq you should be on.

It does take a bit more to figure out where you need to TX and RX at high passes, doppler works both ways and its more noticeable on SSB than FM because of the narrower bandwidth of SSB and the FM sats usually have a wide uplink passband so users don't have to compensate for doppler on the uplink, which is usually a 2M uplink= doppler affect of +/- .003 MHz, whereas the doppler affect on 70cm could be +/- .010 on a high pass.

It is important to remember that when the satellite is coming at you it picks your uplink up at a higher frequency than you are transmitting. just like you do its downlink.

If you are manually controlling a rig/2 radios for operating on the linear sats, it seems it is acceptable to adjust for doppler on the higher frequency. Patrick has some youtube videos out that might help, look for VE7EWK/WD9EWK

Good Luck

 

[KB3TQO]

o.k. I havent tried this yet do to the weather but after playing with some numbers, I found that if you subtract the high uplink freq from the high downlink freq and the same for the low frequencies, you get the same numbers. ie fo-29= 289.9
What is the relevance of this if any?

 

[Qwazyone]

o.k. I havent tried this yet do to the weather but after playing with some numbers, I found that if you subtract the high uplink freq from the high downlink freq and the same for the low frequencies, you get the same numbers. ie fo-29= 289.9
What is the relevance of this if any?

on a non-inverting sat the subtraction will give you a number that you can add to your VHF uplink to get close to your UHF downlink, or subtract from your UHF uplink to find a VHF downlink, I don't think any non-inverting birds are still in operation.

FO-29

up down
145.90 435.90
146.00 435.80