[amsat-bb] ISS Digipeater is back! On UHF this time (437.550MHz)!

[Bob]

As the ISS is approaching, the Doppler Effect causes the frequency you need
to listen to, to appear to be higher.  So you tune your RX to a higher
frequency.

Likewise as ISS approaches you, the Doppler Effect causes you transmit
frequency to be higher.  But the ISS isn't adjusting for that, so you need
to transmit on a LOWER frequency in order to be heard by the ISS.

The adjustments are always in the opposite direction.

73, Bob, WB4SON


On Wed, Nov 2, 2016 at 5:06 PM, mvivona--- via AMSAT-BB <amsat-bb at amsat.org>
wrote:

> Robert,
> I'm not following your explanation, please help me understand.
>
> If the ISS is transmitting and receiving on 437.55, why would you split
> your TX and RX offset directions?Seems to me like you would TX and RX high
> on the approach and TX and RX low as it passes by. Both on the same
> frequency just like you would do on SO-50.
>
>  Michael KC4ZVA
>
>       From: Robert Bruninga <bruninga at usna.edu>
>  To: AMSAT BB <amsat-bb at amsat.org>
>  Sent: Wednesday, November 2, 2016 12:00 PM
>  Subject: Re: [amsat-bb] ISS Digipeater is back! On UHF this time
> (437.550MHz)!
>
> > I'm not so lazy that turning the dial is the end of the world,
>
> I may be reading too much into that statement, but just to be clear...
>
> it is not that simple...  On most FM rigs you cannot turn the knob both
> ways at once, to the left for TX and to the right for RX .  You have to
> tune the TX and RX in opposite directions at the same time every 2 minutes
> or so.  Hence, the suggestion to pre-tune the -/+10, -/+5 , 0, +/-5, and
> +/-10  kHz offsets in 5 memories to make it trivial to make the 5 steps
> during the pass.
>
> -----Original Message-----
>
> From: Robert Bruninga
> Sent: Wednesday, November 02, 2016 11:06 AM
> To: AMSAT BB
> Subject: Re: [amsat-bb] ISS Digipeater is back! On UHF this time
> (437.550MHz)!
>
> Great!    But... Everyone must remember, UHF packet is *not* appliance
> operating.
>
> You must oppositely tune for Doppler on the uplink starting low, and going
> high, while tuning the downlink High and going low.  Best to pre-program 5
> channels and switch during the event.  If you do not do this, you are
> simplky QRM to everyone else, blocking their successes with your failures.
>
> Bob
>
> -----Original Message-----
> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of John Brier
> Sent: Wednesday, November 02, 2016 10:52 AM
> To: AMSAT BB
> Subject: [amsat-bb] ISS Digipeater is back! On UHF this time (437.550
> MHz)!
>
> I didn't see this on amsat-bb yet.
>
> I plan on trying the upcoming 16:45 UTC pass.
>
> https://twitter.com/RF2Space/status/793559573240115200
>
> "#ARISS ISS packet system now operational on UHF (437.550 MHz). #hamradio"
>
> http://issfanclub.com/node/41954#comment-18163
>
> "Due to the failure of the VHF radio in the Columbus module the packet
> system on 145.825 is not possible. The crew just swapped the radio for the
> UHF equivalent and packet is now operational on 437.550 MHz.
>
> The Kenwood D700 radios were augmented a couple years ago by a Kenwood
> D710E radio that was dedicated to SSTV operations. The Russian team soon
> afterwards adopted the D710E as their only operational radio but it was
> never configured for packet operations.
>
> The ARISS team is working on flying replacement D710GA models to replace
> and unify all the hardware. Target for delivery is late 2017.
>
> Submitted by N5VHO on Tue, 2016-11-01 17:14."
>
> 73, John Brier KG4AKV
>
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
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> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
>