Daniel, et al, There might be a bit of confusion about the references used in various posts: note below where one talks about transmit frequency and another talks about receive frequency. The behavior of any satellite's radio signals is always the same, regardless of which band is uplinked and which band is downlinked. To (hopefully) clarify this topic, please note: - Receive frequency is higher at AOS (satellite is approaching you) and drifts lower towards LOS (going away from you) - Transmit frequency must be tuned lower at AOS and is adjusted/tuned higher towards LOS (to match satellite's receiver)
The receive tuning is fairly apparent as you can hear the satellite, but the amount of transmit "adjustment" isn't, especially if you don't have a full duplex radio (as Drew suggests, may be a good investment in stress reduction). The various tables published for the satellites list suggested frequencies, and these are handy if you are adept at changing memories quickly. If you want to (or have to) do it manually, you could use this as a guide: UHF +/- 10 kHz and VHF +/- 3 kHz for a full/high pass of near 90 degrees elevation (at a TCA of only 45 degrees, use half of those shift frequencies... start in the middle of your memory set). Many suggest leaving the VHF uplink at a center frequency: that is convenient but my experience is your signal is not nearly as likely to be successful in a crowded pass (the satellite receiver picks the biggest dog in the pack to repeat).
If you are chasing grids, try very low passes (less than 20 degrees at TCA), use a high gain directional antenna or stand directly in front of your car as a useful reflector (truck beds especially good for this), and just tune the center of the band for both T & R.
73, Jerry, K5OE/G
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Hugo Dominguez, Jr. Sent: Thursday, June 7, 2018 5:50 AM To: Daniel Wight kd7lee@gmail.com Cc: amsat-bb@amsat.org Subject: Re: [amsat-bb] Unsuccessful Uplinks - AO-92
Thanks. All the web pages I read said to perform doppler shift by starting 10 kHz below and work your way up. Even this amsat website has instructions to do it how I am doing it: https://amsat-uk.org/2018/01/26/ao-92-open-for-amateur-radio-use/
I also just noticed that there is a schedule for the L-band for uplink which i’m interpreting that UHF won’t work when the bird is setup for the L-band for uplink. Maybe I was trying to make contact when it was on the L band.
— Hugo Dominguez, Jr.
On Jun 6, 2018, at 21:07, Daniel Wight kd7lee@gmail.com wrote:
Seems like your Doppler shift might be opposite. I normally start high & work my way down during the satellite pass... (For instance, I would start at 435.180 for AO-85 and then work my way down to 435.160 as the satellite 'sunsets' on my horizon). Doppler shift should be higher frequency during approach, near zero when the satellite is overhead, and lower after the satellite passes.
73,
Daniel, KD7LEE
On Wed, Jun 6, 2018, 17:27 Andrew Glasbrenner glasbrenner@mindspring.com wrote: You've discovered one of the reasons full duplex is best on the FM sats...you have no idea if you are getting through, because you can't hear while transmitting.
Got another radio so you can work full duplex?
73, Drew KO4MA
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Hugo Dominguez, Jr. Sent: Wednesday, June 06, 2018 7:41 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Unsuccessful Uplinks - AO-92
I’ve just started playing with talking on satellites. I’m able to hear all the satellites (AO-85, AO-91, AO-92 and SO-50) that I have programmed on my Kenwood TH-D74, which I use with my Elk dual band periodic log antenna. However no one can hear me or responds to me. I’ve only been successful with my uplink (being heard) on AO-91 on several passes. I triple checked my frequencies on my radio and the 67 Hz tone and they are set as follows: Sat. Xmit Tone SO-50 145.850 67.0 Hz AO-85 435.170 67.0 Hz AO-91 435.250 67.0 HZ AO-92 435.350 67.0 Hz These are the frequencies used when the bird is at its peak. I adjust for doppler on 440 by starting out 10 khz less, e.g AO-85 435.160, 435.165, 435.170, 435.175, 435.180.
Any ideas if something has changed from what is published or am I missing something? Like I said, i’ve been able to communicate on AO-91.
— Hugo Dominguez, Jr. _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb