[amsat-bb] No joy with no-84

[Andrew Flowers]

Yes, you need to send a PSK31 signal to turn on the NO-84 70cm downlink.  The standard PSK31 idle signal should work, but an unmodulated carrier won't.  There is a detector circuit that looks for a 31.25 HZ spectral component in the baseband uplink spectrum and that enables the transmitter:

http://www.urel.feec.vutbr.cz/esl/files/Projects/PSAT/P%20sat%20transponder%20WEB%20spec02.htm

I guess the design assumption is that your typical PSK31 message has enough 31Hz AM energy to trigger the detector, as two phase transitions (sequence 00 in Differential BPSK) is the "stop bit" between symbols.

Andy K0SM/2


> On Dec 11, 2015, at 5:17 PM, Joe <nss at mwt.net> wrote:
> 
> If I remember correctly dont you not have to send PSK-31 tones for it to activate?
> Joe WB9SBD
> Sig
> The Original Rolling Ball Clock
> Idle Tyme
> Idle-Tyme.com
> http://www.idle-tyme.com
>> On 12/11/2015 4:05 PM, Mark Lunday wrote:
>> PSK31 50 watts into a vertical, 28120 kHz, sending at 1200 Hz tone.  Nothing
>> heard on 435.350 or +/- 5 Khz.
>> 
>> Mark Lunday, WD4ELG
>> Greensboro, NC  FM06be
>> wd4elg at arrl.net
>> http://wd4elg.blogspot.com
>> 
>> 
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