40 MHz ~ 850 MHz Receiver for FSK Data

[0x34]

Can anyone point me in the right direction? I need to be able to program (uC Controlled) a PLL to tune to a specific frequency between 40 MHz to 850 MHz, then detect and decode any transmitted FSK data. I've located a chip by Texas Instruments (CC1000, transceiver) which covers 300 ~ 900 MHZ, but I need to go lower. Basically, I need to build a frequency scanner capable of this range.

Having little RF design background, the simpler the better.

Any suggestions would be greatly appreciated.

Thanks!
0x34

 

[mneary]

For the front end, consider the tuner module from a television or VCR. You might have to reach back a little in time to get one that goes down to 40 MHz.

 

[0x34]

I'm looking more for a single IC solution to build a circuit around.

 

[k7elp60]

Do you know what kind of selectivity, and sensitivity you need.

 

[0x34]

Based on the FCC’s attempt to narrow bandwidth, I’d like the receiver to work well within 12.5 KHz. A 30 dB selectivity would be fine. An good sensitivity is needed for trouble free and reliable FSK reception and demodulation.

Again, I am new to RF design. I don’t want to become a master in how to design RF circuits. I just need a solution to this problem. The CC1000 (and that series) would work perfectly if it was capable of operating down to the HF band range (40 MHz to 950 MHz).

 

[Mikebits]

Have you developed a plan for your LO? It seems that you will need multiple VCO's to cover that broad range of tuning.

 

[0x34]

The CC1000 has a built in PLL, programmable by the host uC. I was hoping to find a single chip solution with the same thing.

I look at the Bearcat range of portable frequency scanners. I know they contain ASICs, designed specifically for their use. However, they basically do what I need (minus FSK decoding)! I need a programmable receiver chip capable of tuning to the wide range of frequencies used by our customer base.

 

[Mikebits]

The CC1000 has a built in PLL, programmable by the host uC. I was hoping to find a single chip solution with the same thing.

I look at the Bearcat range of portable frequency scanners. I know they contain ASICs, designed specifically for their use. However, they basically do what I need (minus FSK decoding)! I need a programmable receiver chip capable of tuning to the wide range of frequencies used by our customer base.

You will note from the CC1000 data sheet that it's band coverage is limited by the VCO which is set by L101. Although the data sheet shows that the CC1000 can operate from 300 - 950MHz, it cannot cover the entire range per a single configuration, rather is band selectable such as 315MHz/ 433MHz/ etc.

I doubt you will find a single chip solution as the VCO tuning range will be a problem, but never say never, I could be wrong

 

[k7elp60]

There are several manufacturers of wide band receivers, perhaps that might be a solution.
Here is a link
https://www.icomamerica.com/en/products/receivers/pc/pcr1500/default.aspx

 

[kchriste]

I doubt you will find a single chip solution as the VCO tuning range will be a problem, but never say never, I could be wrong

I think you are right.
One solution is to use two oscillators running at a much higher frequencies and mix them to create the LO. Much easier to tune a VCO from 1040-1850 Mhz and mix it with 1000Mhz than tune from 40-850 Mhz directly. D'52' won't find this in a single IC solution.

 

[Papabravo]

Without some RF design experience and some pricey equipment to measure and analyze the results his chances of producing a working circuit are so close to nill as to not be worth mentioning.

Never mind the issues of what kind of antenna he plans to use. At those frequencies it gets tough to capture waek signals and control losses.

If you're serious about the application I'd get a Kenwood R-2000 general coverage receiver($400.00 Used) and tap the signal at an appropriate point. Once you get that to work you can pursue alternatives.

 

[Mikebits]

D'52' won't find this in a single IC solution.

lol, having fun with hexadecimal are we

 

[kchriste]

lol, having fun with hexadecimal are we

That, and just checking to see if people actually READ my posts.

 

[elektro77]

thank you thank you

 

[picbits]

thank you thank you

Why ??????

 

[VISN]

**broken link removed**
is a tv tuner with 3 local oscillators that are band switched to cover the range. It (or one of the other TI tv tuners) was used in one of those cheap Chinese tuners but I cannot find an application note, so you need to dicipher the Datasheet. Just L/C/R and a 4Mhz xtal, chip controlled by i2c, one of the devices does not need 33V for the varicaps - from what I remember. The most important other component is RF shielding.
You may have difficulty buying the device, though you might get a sample from TI.