Radio Field Strength Meter.

[eclectic]

Field strength meter. Some rambling thoughts.
Prompted by
http://www.picaxeforum.co.uk/showthread.php?t=11463&page=4
postings # 29 – 32.

Use a quick simple FSM, for example:
http://www.zen22142.zen.co.uk/Circuits/rf/sfsm.htm

Instead of the DMM, use a simple Op Amp and ReadADC10 Picaxe circuit.
Transmit the values over a “standard” Picaxe 433 MHz arrangement.

Scenario 1.
I'm at home, with my transmitter and I'm adjusting my new Tx antenna.
The fixed receiver / FSM sends me data.

Scenario 2.
I go walkabout, carrying the transmitter. I log my position on a map.
The home receiver sends me info. I write it down.

Scenario 3.
Going further, using Eeprom (and even GPS)
for an automated logging system to make your own Polar Diagrams.

I know it's done for “real”, by the professionals, using “serious” equipment,
but, AFAIK, not yet with a Picaxe.
(And, this could all be breadboarded and re-cycled.)

And, if it doesn't work, you've still had a walk in the fresh air.

e

PS 1. It could also be done using a receiver with RSSI

PS 2. OA91 diode example
http://www.rapidonline.com/Electronic-Components/Discrete-Semiconductors/Signal-Diodes/OA91-Germanium-point-contact-diode/73379/kw/germanium
(I'm sure there are many alternatives.)

 

[manuka]

Interesting thoughts there Eclectic- what freqs. (433 MHz?),power (~10mW) & ranges (100s m?) had you in mind? As 433 MHz ranges are quite puny (~100m),you can almost shout "Wave your arms if you still hear me". But following your thoughts, I can see a PICAXEd HopeRF pair sending back at least tone FS info- low tone= weak, while higher= strong etc. Maybe this could be set up as a "store & forward" simplex repeater? Feel free to hack the setup at => http://www.picaxe.orconhosting.net.nz/all3.jpg

Over past decades as a ham I've run across all manner of DIY FSMs, but many were intended for quite high powers (Watts-100s Watts). I've also dabbled with smart simplex repeaters ,which let you hear the quality of your transmission too. See a PC based approach=> http://www.synergenics.com/sc/

You really can't beat having a mate at the far end however. Issue him with a cell phone (or even a VHF CB) & suitable amber fluid, & he'll be putty in your hands during all manner of local Tx tweaking. Much 433 fine tuning of course relates to antenna type, elevation, matching & orientation- just the sort of thing a relaxed & patient far end responder is needed for. (Especially if you fall off a ladder & need an ambulance)

NOTE- store & forward simplex repeaters are illegal in some countries on some bands, but they certainly improve ones "on air style" ! Radio Shack offered one some years back (19-345, but now discontinued) with a 30 second voice recorder that suited many.See => http://www.youtube.com/watch?v=O55KRm2Cw5E

I can't see any 433 MHz hassles however, as almost anything goes on that spectrum slice. Stan

 

[eclectic]

Thanks for the reply Stan.
It was literally vague musings.

Totally inapplicable to my small house and garden.

e