I am planning to implement a small software-defined radio with a
bandwidth
of say 50-300 MHz at first. The system should be able to receive AM, FM,
PM
signals over the mentioned RF spectrum with upto 10MHZ baseband
information.
This would require an IF of at least around 11-12MHz. Can u ppl help me
in
choosing an appropriate RF front-end design for the hardware system?
I am facing a problem in selecting the right analog down-conversion
system
design which would possess a good IMRR, sufficient linearity and an
acceptable SNR over the desired bandwidth. If I am to tune my radio
through
the software, which I want to, I’ll have to set dynamic filter
characteristics to the RF amplifier stage(before mixing) to facilitate
image
rejection. Can a superheterodyne down-conversion serve my requirement??
If
not, what kind of receiver system should I use…? Is Direct-Conversion
technique implementable in my case? Please share your knowledge on these
matters.
I basically want a 10MHz IF for being able to receive Cable TV signals
as
well. Of course this will be quiet complicated but I will try to doing
it.
With that I may try touching ISM bands later at some pt when I have the
required receive-boards…
choosing an appropriate RF front-end design for the hardware system?
So you are not interested in HF bands or weak signals? and you
want to “see” a 10Mhz bandwidth signal.
I think these strong, broadcast makes your job a LOT easier.
I’ve read about
people using tuners designed for cable set top boxes. “Microtune”
makes a bunch of these that cover your range. I think you just hook up
one of these microtune devices to an ADC that samples at about 30M/Sec
and 10 to 12 bits per sample. At 30M/sec you don’t need quadrature
clocks or QSD or anything like what SR40 does
The big issue will be how to get that data stream into the computer.
If it were me I’d format the data is UDP packets and put it on a
Gigabit Ethernet cable. UDP is very easy being a one way stream
with no handshaking involved
