How to design 32ch receiver system in adjacent channels with 25khz channel spacing?
How we can design 32ch receiver system in adjacent channels with 25khz channel spacing and 2400bps.
all RX system should operate simultaneously.
-How many receivers & Transmitters are active at a time
-What is the transmitter power
-What is the typical receiver power (Transmit power - path loss - antenna effeciency)
-Is this a 1 transmitter to many receivers system? Are they all operating at the same time?
-How cost sensitive is this?
-What is the freqeuncy band you are planning on using?
Dave
www.keystoneradio.com
---we have 32 TX at the same time(correspond to 32 RX ,one by one)
---6W
---16dB antenna at RX and 10dB at TX( no LOS, in civil area, outdoor TX and RX)
---32ch RX system in only one unit and get data from 32 discrete TX at the same time.
---no cost problem,cost is not a factor in design
---1MHZ bandwitdh at 400-500MHZ range(you can recomment new band)
So 32 transmitters and 32 receivers, in a 1-1 relationship (one transmitter talking to one receiver) in a system, with 800 kHz band (32 * 25 kHz).
Now, you need to figure out a couple of things. First, you need to determine the baseband SNR that you need to decode a transmission. I'm not sure how you are going to determine this, part of this may come from the vendor of the chipset you are using. Failing that, look at some intro communications theory books and figure out, from the modulation type (FM/PM/QPSK/etc) what the SNR you need is.
Once you have this, you can determine the receiver minimum signal you can receiver
Receiver SNR, assume 4 dB Receiver Noise figure, gives you minimum receive power, back that out through the antenna gain, assume an urban path loss, and you can get how far you can transmit and receive.
Next, you can assume that you have a receiver, as far away from it's transmitter as you can get (Minimum input power), on channel N, and it's next to the transmitter on channel N+1. From the difference in powers, you can start determining the filter requirements for the receiver.
This is a fair amount of work, can you get something off the shelf to do this?
Dave
www.keystoneradio.com