MarconProp, a VHF receiver controlled by a Propeller

MilitaryRadio

Hi,

I used a Propeller to control a VHF receiver.

The Prop controls:
-·PLL frequency,
- Signal Strength,
- Squelch (muting),
- PLL lock,
- reads user input from a keypad
-·displays output on a LCD display.

The Propeller is not only restricted to robotics use ... it can really be used also in the telecommunication world.

Paul

dwalton

Paul,

This looks very impressive. What frequency range does it support? Is this a 2m receiver? I would be interested in learning more about what you built. Is that a custom board for the propeller?

Drew

MilitaryRadio

Hi Drew,

This is a FM 70Mhz transceiver build to experiment this Radioamateur band.

With some minor modification the receiver is able also to work also on 144mhz.
Propeller controls in real time through the internal cpus all the working parameters: the pll, the received signal level, the lock of pll.

Now I'm designing the Transmit module that will be equipped also with a PLL. The CPU will monitor the power transmission, the SWR, and other ...

MilitaryRadio

Some more detail about the CPU board:

The keypad is read through a 74C922 encoder, the cpu has also a clock DS1302, the analog digital convertion is performed through a PCF8591 ADC. The display is directly connected to the CPU. The EEPROM is programmed via a RS3232 IC.
On the CPU board it is present also a beeper.

The PLL installed on the receiver is a Fujitsu MB1502.

Phil Pilgrim (PhiPi)

Paul, this is an impressive feat, especially since it also appears that you designed and built the RF board as well. (The trace routing styles between the two boards are very similar, as are the typefaces.) Can you tell us more about the radio itself? Single conversion? Dual conversion? What kind of detector? Perhaps share a schematic? Where did you get the Mitsumi frontend?

Thanks,
-Phil

MilitaryRadio

Hi Phil,

I started this project about one year ago. I designed both CPU and RX cards. I've to design the Transmitter module yet. When everything will be completed I will assemble all in a case.

The receiver is a double conversion radio. First conversion is on 10.7mhz, second on 455khz. I used two high quality filters (murata) in order to get a good selectivity. The mc3361 is the core of the FM receiver, close to it there is an LM358 to drive the s-meter. An LM386 IC amplifies the audio coming from the mc3361. In the picture of the radio you can see the tuner that is a mitsumi 407-a26 I found and purchased it here:

http://www.alltronics.com/cgi-bin/item/92A027/search/Synthesized-Tuner-Board

The tuner sensibility is very high about 0.3 microvolt, has an internal oscillator, is able to work from 50 to 150 mhz and provides an output on 10.7 mhz.

Post Edited (Paul65) : 3/15/2009 10:43:04 PM GMT

Jay Kickliter

How fast can this step through frequencies? I see on the schematic that there is a signal strength out. Could you use this to make a Prop-based spectrum analyzer?

MilitaryRadio

.... I think it's not possible to use it as spectrum analyzer

mikediv

Paul very nice, I am not clear tho are using the prop to sift through the frequencys? Would you be willing to show us the code? The reason I ask I have an Icom 7000 and would love to be able to have a better interface for selecting which freq to scan
Thanks
·

MilitaryRadio

Propeller CPU controls the MB1502 PLL through a three wires interface: clock, data, latch enable. Attached you will find the code to control it.