changing transmission frequency
For e.g. if variable "X" is 0 then frequence of transmitter should be 400-420 MHz and if "X" is 1 then frequency should be 430-440 MHz.
Can this be done? And how?
Yes it can.
Just get and Amp that meets your Tx Power from 400Mhz to 450MHz and your done.
Now, by setting X to 0 or 1 you will need to explain what spec's you need met
from band "0" to band "1". Because you can just change your LO to go from
each band. You can also put an RF switch at the output of the Amp and have each
path have it's own Band Pass Filter...
But first describe in more detail what you are trying to do, to get better answers.
Also it doesn't look like that ER400TRS module, can transmit over that wide of
a band width.
The "Easy Radio" modules are designed to use license free bands only and can't be tuned to different frequencies, although
the Chipcon/TI CC10xx chips would allow. Other radio modules, that let you use your own firmware, e.g. from Hope RF,
would be better suited for this purpose. Local regulations should be considered, however.
Actually I am planning to make a small wireless network as my project in which I want to show voice and data communication between different users.
There will be more than two users having a device containing a transceiver, microphone and a speaker and there will be one central PIC with a transceiver.
For making one such device I searched for transceivers and found ER400TRS to be quite easy to use. It has got 10 channels ranging from 433.23 to 434.35 MHz.
When user "c" wants to communicate to user "a", it sends a bit pattern as:
1010 0001 0011
1010= call generation code
0001=A
0011=B
On receiving call request, PIC will check whether A is free and if "yes" then it will allocate channel 1 and channel 2 (assuming these channels to be free) to A and C.
Now "A" transmits at channel 1 and receives at channel 2 and vice-versa in "C".
I just want to know how can I set transmission and reception to a particular channel. And also any suggestion related to anything will be appreciated as I am quite new to RF.
Thanks
ER400TRS can't be changed on the fly. A channel set command always stores the new frequency setting to the EEPROM. The
command is also transmitted on the air. Due do this fact, it's unpleasant to frequently change the setting in operation,
although still possible if the frequency doesn't exhaust the EEPROM.
As another point, adjacent channels can be also reveived with limited reduced sensitivity. The module has "DCS" feature
that blocks these receiption by an additional channel code, but of course, it can't prevent interferences from neighbour channels.
I suggest an ER400TRS datasheet literature.
Thanks for the reply :)
Basically I want to assign a particular channel to each user as it's reception channel.
Now suppose user "A" is communicating with "C", then it should transmit in the channel assigned to C's receiver and after this if "A "wants to communicate to "B", then it should transmit in the channel assigned to B's receiver.
What I want to know is can the transmission frequency be changed in accordance with different receivers.
What I have planned for it is: I will assign different values to the user's receiver's channel in my code.
e.g.
1011 channel 1 (user A)
1100 channel 2 (user B)
1101 channel 3 (user C)
1110 channel 4 (user D)
Now suppose data from central station received by the user C is like:
1111 1100
1111: change transmitter freq
1100: channel 2 for B
After this, the user C starts transmiting in channel 2 regardless of whichever channel it was transmitting in before.