On 05/24/2012 09:18 AM, Peter wrote:
We would get allocation of a single channel from the frequency coordinators, who can continue to treat it as "one channel", but then we should make sub-allocations within that channel. So, if we get 12 or 20 KHz from the coordinators, that is potentially 4 or 8 2.5 KHz channels for Codec2 users. And all of those users enjoy about 3 times the range that they would have with D-STAR, or better power budgets for handhelds.Well, my area is populated (London). But, not so many radio operators. VHF/UHF is pretty quiet most of the time.But, even if it was busy. The band plan (for the UK at least) has channelized setups. For low bandwidth use, an SSB radio using the FDMDV modem would be the best bet as it exists already?
Unfortunately, FDM is not the best solution for mobiles. It requires linear amplification, and you end up throwing away much of your power budget in heat. I think a narrow GMSK channel might work better.
Don't use standard FM radios. Let's please treat standard FM radios as a temporary platform. We can do so much better than them, and I think the main sales points of codec2 to the average ham are that we /can /do better.So, I guess my point is - how are we to implement a low bandwidth solution using standard FM radios?
Hoo boy, do we have problems! 70 cm used to be our most-used band. U.S. military shares the spectrum with us, and we are the secondary user while they are primary. They improved the sensitivity of the PAVE PAWS system, and started to get interference from ham repeaters. They made most of our repeaters in the Silicon Valley / San Francisco Bay area severely reduce power.Do you have problems on 70cm too?
So, you can see the pressure we're under. Alinco has started making a 220/900 HT for our area. But spectrum efficiency is going to be a big part of the solution, too.
Thanks
Bruce
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