It looks like the available NCOs don't get high enough in frequency. I think we
need 350 MHz to over 2 GHz.
On April 20, 2014 7:47:46 PM PDT, Bruce Perens wrote:
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>On April 20, 2014 7:18:07 PM PDT, David Rowe wrote:
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>>Bruce - I don't think TDMA will require PLL locking, tx and rx would
>
On April 20, 2014 7:18:07 PM PDT, David Rowe wrote:
>Bruce - I don't think TDMA will require PLL locking, tx and rx would be all on
>one frequency.
Not sure this is always the case for Whitebox. And we are looking at
low-phase-noise DDS chips, and they still have a VCO. If you know of a rea
Hi Daniel,
Yes a SDR radio would be a good way to build this.
Bruce - I don't think TDMA will require PLL locking, tx and rx would be
all on one frequency. If required, a NCO (i.e. DDS) can change
frequency instantly. Re PA linearity, it would be nice if the tx power
can ramp up reasonably ge
Hi Daniel,
I like the idea of TDD for a repeater instead of FDD. On HF it would give you
break-in, but at the cost of some mostly-wasted bandwidth.
Since HTs are power-limited, a modem that does not require linear amplification
might work better for them. GMSK or C4FM, etc. There is a lot of ta
David,
Thanks so much for your input!
That's the idea a super cheap VHF repeater(no duplexers), also thinking of
doing something with and SDR to allow one repeater to manage like 10
channels in a 25khz of spectrum. But that's if I can get the timing figured
out.
Yes it does seem to be an issue on s
Hi Daniel,
That sounds very cool. Another nice application is single channel
repeater work for VHF. Need a radio that can tx/rx switch fast enough.
Couple of ideas:
1/ Have longer timeslots than 20ms, like say 200ms, estimate the rx
symbol timing over that window. The timing is probably const
Hello Guys,
I've been playing with the FDMDV modem to see if I can get it to support
Time Domain Duplexing(TDD), with the end of goal of making full-duplex
voice in around 2KHz.
Currently I have the modem configured at 100 symbols/second with 14
carriers spaced at 125Hz it works out to 2800bits/s.
