DIY R/C Frequency Monitor

[yctseng]

Actually, this idea comes from PC-CAM's RC-MON project. Since that monitor
can only watch one frequency at a time. And it require X'tal to put into the
receiver. So there will cost a lot if you want to see all the band's usage.
I'd search some receiver and decide to build mine using MC3362 in my hand.
MC3362 has a VCO inside and can operate up to 200MHz (I think). To read the
frequency, I select the "LCD Frequency counter" using PIC 16F84A with pre-
scaler HD-10551 (devide by 40 and operate up to 250MHz). I also modified the
code for that PIC (orignal is devide by 64). It operate with IF shift to add 10.7
MHz which read the frequency comes from VCO pin 20. Following are some of
the pictures. Suggestions are welcome..

[Mr.RC-CAM]

Looks good. There is much to be learned about an unexpected RF signal if you can listen to it. Many times the "noise" will not be another R/C transmitter and hearing the modulation is a real plus. So, an audio amp & speaker would be a nice addition.

[simingx]

That's very interesting, could you provide more details? (Schematics, code etc etc...) :)
I might have some 3362's lying around...

[yctseng]

The Counter using PIC 16F84 is very common. You can search using google and
find lots of examples. I use JK1XKP's (http://www.saturn.dti.ne.jp/~khr3887/lfcd_e.html) version but did some modification of his code.
He use TD7104P (http://www.saturn.dti.ne.jp/~khr3887/lfcd04kairo.gif) which is devided by 64. I use HD10551 which is devided by 40.
You can select pre-scaler which available arround you. The most important is
the IF shift setting function. The JK1XKP's code can set any shift frequency just
by pushing the switch. I also use 12.8MHz TXCO as the base clock which keep
the counter read correctly most of time.

[TheAdrian]

I am working on a spectrum analyser project for the 35 MHz band. The idea
is to display the spectrum on a graphical LCD display. At high resolution it
can displays one channel and its neighbours on either side at a resolution
of 200 Hz per pixel. At low resolution it scans all the channels at a resolution
of 5 dots per channel.

My plan is to synthesize the local oscillator frequency in steps of 10 KHkz.
Mix to an intermediate frequency of 21.4 Mhz and filter with a 38 KHz
bandwidth crytal filter. Capture 2 * 336 samples at 1344 KHz into a PIC
using a sampling A/D converter. Fast Fourier transform to compute the power
spectrum, convert to dB and display on the LCD.

I have not started the hardware yet; I am still working on the software.
First I need a 336 point FFT optimised to run on a PIC. The PIC is a
26F20; it has 3900 bytes of memory, which should be enough as the FFT
algorithm does not need extra workspace. My best guess is that performance
will be about 15 transforms a second.

[yctseng]

For the receiver part, I use MC3362 sample schematic. Or you can reference
some HAM radio website for more informations about control the frequency
using VR. I use 100K 20-turns VR that would let the tune more easy.

[yctseng]

I also setup a socket in VCO pin which can replace the coil for different bands.
Of course, the RF amp. will be replaced the same time.. :)

[lazy-b]

Yctseng, Thats was a nice project.......keep us posted on its performance.....I just wonders if its Selective enough to detect adjacent channel.

Did anyone try using TV-TUNER/FM-Tuner card use in Computer, might just need a software to allowed monitoring 72 MHZ, 40 MHZ, 36 MHZ, 35 MHZ.

[yctseng]

Yctseng, Thats was a nice project.......keep us posted on its performance.....I just wonders if its Selective enough to detect adjacent channel.
Of course, It use 10.7MHz x'tal filter and that can narrow the bandwidth below
5KHz. I'd try to put my TX far away (about 10m) and tune the frequency.
Have I tell you I use the Bruce Abbott's PIC decoder and it have one LED to
show the signal is been decoded correctly. After test my rig, it shows the
bandwidth is as I expected. Just for your reference... :)

[yctseng]

I just found one good Frequency Counter from ARTRA FP50 kit (http://www.artra-qrp.com/fp50/fp50.html)
Maybe I can try to replace my display part just using 16x1 LCD.

[Acetronics]

;)

Hi,Y.C.

Have a look here ... : http://www.llm-electronic.com/html/non_embarque.htm

device is called " Model - scan "

Alain

[yctseng]

;)

Hi,Y.C.

Have a look here ... : http://www.llm-electronic.com/html/non_embarque.htm

device is called " Model - scan "

Alain

Thanks Acetronics, nice product. Actually I have ICON IC-T90A which is all-band
receiver from 0.495MHz to 999.99MHz. This project is just for fun and maybe some one want to enjoy DIY (like me) and share experience.. :)

[lazy-b]

YCTseng, That would be good, if it can detect two Adjacent Channel, cause my ICOM R1 Portable Wide Band Scanner 500KHZ to 1.3 GHZ can not detect two adjacent Channel, If I try to let it scan the whole band of 72.000 to 72.990 step 10 KHZ, my Transmitter is at 72.350 MHZ........after Scanning, my ICOM R1 would register a 72.340, 72.350, 72.360 as active channel.......Maybe my ICOM is not Narrow enough to detect 2 adjacent channel.

Great Works, Keep us Posted on your Project, Hope you can make for 72 MHZ, 40MHZ, 41 MHZ ,35 MHZ and 36 MHZ (But the Most popular is 72 and 40 MHZ) .....in Just one Gadget.....Same Gadget posted my Alain (Acetronics)

In the Philippines, there is no frequency control here, thats why we have all those Frequency.

Ellion

[yctseng]

Just found a very good and special website. There is another Freq. counter which can
set IF using windows GUI and automaticly calibration just using RS232 2pins. It also use
LM592 as the pre-amp instead of transistors. That IC is just a general purpose video and
floppy disk head amplifier which can support up to 120MHz. Quite easy to build
although it need to prepare one more PC with old MS-windows. That program can't
support WIN-XP . I'd build one and maybe some of you will get interest on it. Share
with you all.

http://pageperso.aol.fr/artra68/fp50/fp50.html?f=fs

Translate into English :

http://babelfish.altavista.com/babelfish/trurl_pagecontent?lp=fr_en&trurl=http%3a%2f%2fwww.artra-qrp.com%2ffp50%2ffp50.html


My work :

[yctseng]

Just complete part of my 2nd generation R/C Frequency Monitor. I use
MC145163 PLL IC and MC3362 for VCO and receiver. Quite easy..!! :)

[yctseng]

Another PLL with VCO tune to 34.585MHz (35.040 - 0.455). Output connect
to GWS receiver's X'tal pin. After test, work very well. I'd proved this idea
and maybe some RC company can work out some small product like this to
replace the X'tal. Just use the orginal receiver and plug-in through the X'tal
pin. Everyone can have multiple channel just use this kind of solution. :) :)

[lazy-b]

Yctseng: Thats a Great Idea, Now we can convert all our Regular Receiver into Synthesizer........One thing I do not like synthesizer is those Switches to change channel, sometimes due to loose contact in switches, this will change channel in MID-AIR and cause Crashes........This actually happen to my friend, he is using a Transmitter with a Synthesizer Transmitter Modules, while flying his Helicopter, somehow the Tranmitter Modules changes channel in MID AIR and crashed the Helicopter.

Maybe you can use a PIC controller to control those CHANNEL switches......can use a simple 3 PIN (+5Volts,I/O pin, Ground) for programming the Channel......or might use 2 PIN for Resistance programming 1K for Channel 1, 2 K for channel 2.....50K for channel 50.......this will just need an 8 Switches and 8 Resistor for 256 Channel......for 50 channel this will need only 6 switches and 6 resistor.....resistor is 1K + 2K + 4K + 8K + 16K +32K , all resistor is connected in series, and all Switches is connected across the resistor.

hope you can make for 72, 40 , 35 , 36 MHZ.

Nice Works.....Keep us Updated on your project.

Ellion

[yctseng]

Yes,of course. This is just a prototyping. My idea is like your described. But
on the other way, it reduce the flexibility changing the channels in the fly field.
Or I must bring another controler like notebook PC or PDA to setup the
frequency. I know the "Shadow" receivers using this way.
About using the PIC to control, I'm not an expert writing the code. I need some
one to help me. I have seen one sample circuit using 16F84 to control MB1504.
Maybe this is a way I should have a try.

[Acetronics]

Hi, YC

I still have in my old schemes ... one of the first RC freq. synthetizers published, which was just intended to replace the Xtal. ( 1 Band per PCB ... of course !!!.)

This was 35 Years ago ...

It was built around a MC145151 and a LM324 AOP ... and coding was done by switches.
a Little trickier was with an EPROM and BCD coding wheels.

Let's be a little up to date and let's replace the 145151 by a 145106 - or similar ( serial programming ) and a PIC to generate the serial data from a Keyboard.

What about ??? Want me to dig this out ???

Alain

[yctseng]

Hi Alian;
Thanks ! Any comments are welcome. Yes, this maybe a good start to try.
Actually, I'd build one type of transiver for trainning in ARMY using MC145106
17 years ago. It operate in 50MHz and have FM and CW mode. I use HD10551 to
devide 10 and then control by MC145106 PLL. SO it can step by 100KHz. I still
have about 20 pcs of this IC in my box. Maybe you can post some better circuit
and I can have a try.
I still thinking about how to control the PLL more easy and stable. Small pins
and dip switch maybe fail cause by vibration or ages. Any other better idea ?