Newbie radio link issue

[Dave]

skimask, I bet your sending data continously. As I ran these tx/rx modules on the bench I noticed that the more data they sent continously the better the receiver alligned to the transmitted signal. I send 1 packet of 32 bits (64 manchester bits) with a sync pulse once every minute and the best reliable baudrate I can get is 500 baud manchester. I suppose if I sent a couple thousand bits I might pick up 1 or more packets at 380 ft.. Are you using the stock antennas or have an external antenna?

Dave Purola,
N8NTA

[skimask]

skimask, I bet your sending data continously. As I ran these tx/rx modules on the bench I noticed that the more data they sent continously the better the receiver alligned to the transmitted signal. I send 1 packet of 32 bits (64 manchester bits) with a sync pulse once every minute and the best reliable baudrate I can get is 500 baud manchester. I suppose if I sent a couple thousand bits I might pick up 1 or more packets at 380 ft.. Are you using the stock antennas or have an external antenna?

Dave Purola,
N8NTA

Stock antenna's that came with the modules (the little whips), not really placed up high or anything, eye level on the TX, waist level on the RX. Not continuous data, however, I 'preload' the TX with a decent amount of sync (64 x $AA, I read somewhere once that these types of TX's want about 5ms of preamble before they really work well), then 2 $55's, then send the temp data word, repeated 4 times.
The RX won't take the data unless it first sees 32 x $AA, then the 2 $55's, and it really won't take the new data unless it sees 3 out of the 4 data words equal each other. I set it up so the TX PIC only wakes up once a minute and it only sends data if the temperature changes more than 1 degree F. The RX has an RTC on it and keeps track of time (incidentally, the RX also powers down for 55 seconds after receiving the data because I know it'll never get another packet before that, every last bit of power at both ends, even though the RX is wall-powered).

And for the physical impediments to RF transmission:
TX antenna -> concrete block wall -> open air for 275ft (give or take 10ft) -> house siding -> stud wall with insulation -> sheet rock wall x2 -> RX antenna.
But that's just my happy story my good transmission. I suppose if I would've got the next module down the manufacturing line, I could just as easily be running 1200 baud for 50ft at most.

[George]

Sounds hopeful anyrate, I had a look at the paralax website and am wondering what the other components on the board do - the Linx website say there r no external components required and show schematics of it hooked directly to a PIC - any ideas?

[skimask]

Sounds hopeful anyrate, I had a look at the paralax website and am wondering what the other components on the board do - the Linx website say there r no external components required and show schematics of it hooked directly to a PIC - any ideas?

I couldn't tell you what they are...power supply filters, antenna matching type stuff, who knows... What the website means by 'no external components required' probably means that nothing is needed outside of the pins that connect it to the board...which is correct. I connect directly to the PIC and the power/ground rails.