problem with sending data using RF module

[JD123]

Check your comp drawing. If it's correct, you're sending the comp to rails. I think you ment to take the output of the rec to the inverting input, not ground. The 100uf cap is a bit much. I'd use a 1uf or even a .1uf.

Also, what's the signal look like at 1.8khz (same speed as the tx). Your receiving scope pix says you'r reading at 19.3mhz. If your data is riding on the noise at 1.8khz, you'll need to filter the noise in a LF band pass amp.

[mister_e]

There's a load of noise indeed... with that signal.. i don't feel the comparator will be of any help... need something else indeed...

I have to ask, The RX signal is the one [from the Receiver Without your comparator connected too and a Pull-up on Vcc] or at the output of your LM741.. which will never work as is (forget pin 5 and 1, and connect pin 3 directly to RX pin).

Maybe the following link will help you a little bit
http://www.uoguelph.ca/~antoon/gadgets/741/741.html
http://www.ecircuitcenter.com/Circui...mp/op_comp.htm

[rano_zen06]

There's a load of noise indeed... with that signal.. i don't feel the comparator will be of any help... need something else indeed...

I have to ask, The RX signal is the one [from the Receiver Without your comparator connected too and a Pull-up on Vcc] or at the output of your LM741.. which will never work as is (forget pin 5 and 1, and connect pin 3 directly to RX pin).

Maybe the following link will help you a little bit
http://www.uoguelph.ca/~antoon/gadgets/741/741.html
http://www.ecircuitcenter.com/Circui...mp/op_comp.htm

It' s not the output from my LM741. At the moment my Rx data pin connected directly to port A.0. also not using pull up on vcc at that time. In your opinion., should I use filter??

[mister_e]

I'm really in between few things... it would be nice to have one of those receiver here to do some test on my side... as shown here there's a load of noise... but your Vmax measure says 80mv, Vamp 136mV (assuming the measure is good... we don't see the v/div input setting)... i don't think it's really the real big problem. the TX show an amplitude of 2.72V :eeK: not sure how good it is for your TX module.

What i suggest for now, is to use 2 channel on your scope, 1 for TX, 1 for RX, Use 5v/div probe scalling for TX, 500mV - 1 for RX, and post the result(screenshot) here.

[dhouston]

I have tested a SAW controlled transmitter and superregenerative receiver from the same company.

• http://www.yishi.net.cn/product_deta...?id=54&fid=177
  http://www.yishi.net.cn/product_deta...?id=52&fid=161

Given that they use the same terminology to describe the outputs of both receivers (i.e. output signal is TTL and can be directly connected to decoder) I am confident that the output of your receiver is digital, as is the output of my test receiver. There is not much you can do with a comparator to reduce the noise. Your best bet is to use the techniques I've recommended repeatedly.

[dhouston]

Furthermore, if you look at the block diagram in the datasheet from the HiMark RX3310A chip, you will see the comparator in the output circuit. Adding another will not help.

[Bruce]

Wow that really is some sloppy output stage. Try sending a continuous data stream of an
equal number of 1's & 0's like 55h with a 1mS pause between each byte of data, and capture
a scope shot of this.

I'm curious is this data-slicer is ever squaring anything.

[rano_zen06]

Hello Guys..Thanks for all the advice
Now my Rx module works fine in a short distance around 5-6 feet.I just add 10k pull up resistor at Rx data pin and 10uF at Vcc.But If I move more than 6 feets, my Rx module start receiving noise and my LCD will display wrong counting numbers.But It's fine to me.At least it's work.I think maybe the problem is from the antenna.I just use a small wire with length 10cm each for my Tx an Rx.So anyone here have any ideas about the antenna??
Now I'm moving foward to send a data from my keypad. IF I pressed pad1,pad2 and so on..my LCD at transmitter board will display BUS01,BUS02....What I want to do is send the word "BUSxx" each time I pressed the keypad and display it on my LCD at receiver board. So with help and some advice from mister_e..I wrote the code below.But It's not work even I Connect the transmitter and receiver pin directly.
The FAct Is..I'm very poor with the coding..please help me guys..

Tx part

@ device HS_OSC, LVP_OFF
define OSC 20

DEFINE LCD_DREG PORTC 'LCD data port
DEFINE LCD_DBIT 0 'LCD data starting bit 0 or 4
DEFINE LCD_RSREG PORTB 'LCD register select port
DEFINE LCD_RSBIT 7 'LCD register select bit
DEFINE LCD_EREG PORTB 'LCD enable port
DEFINE LCD_EBIT 5 'LCD enable bit
DEFINE LCD_RWREG PORTB 'LCD read/write port
DEFINE LCD_RWBIT 6 'LCD read/write bit
DEFINE LCD_BITS 8 'LCD bus size 4 or 8
DEFINE LCD_LINES 2 'Number lines on LCD
DEFINE LCD_COMMANDUS 2000 'Command delay time in us
DEFINE LCD_DATAUS 50 'Data delay time in us

TRISC = %00000000 'Set port B as output
TRISB = %00000000 'Set port D as output
low PORTB.6 'Set the R/W bit to low

pause 1000 'wait until the LCD initializes

' Define program variables
col var byte ' Keypad column
row var byte ' Keypad row
key var byte ' Key value
TransmitterPIN VAR PORTA.0
YourByteVar var byte
INCLUDE "modedefs.bas"
Synk VAR BYTE
Synk = $55
DEFINE CHAR_PACING 500

ADCON1 = 7 ' Make PORTA and PORTE digital


Pause 100 ' Wait for LCD to start

Lcdout $fe, 1, "Key In Bus ID" ' Display sign on message

loop:
Gosub getkey ' Get a key from the keypad
Lcdout $FE, $C0, "BUS",DEC2 key ' Display ASCII key number
PAUSE 200
Goto loop ' Do it forever

' Subroutine to get a key from keypad
getkey:
Pause 50 ' Debounce

getkeyu:
' Wait for all keys up
PORTD = 0 ' All output pins low
TRISD = $f0 ' Bottom 4 pins out, top 4 pins in
If ((PORTD >> 4) != $f) Then getkeyu ' If any keys down, loop
Pause 50 ' Debounce
getkeyp:
' Wait for keypress
For col = 0 to 3 ' 4 columns in keypad
PORTD = 0 ' All output pins low
TRISD = (dcd col) ^ $ff ' Set one column pin to output
row = PORTD >> 4 ' Read row
If row != $f Then gotkey ' If any keydown, exit
Next col

Goto getkeyp ' No keys down, go look again

gotkey: ' Change row and column to key number 1 - 16
key = (col * 4) + (ncd (row ^ $f))
Return ' Subroutine over

Main:
High TransmitterPin
pause 200
SEROUT TransmitterPIN,T2400,[Synk,Synk,"~",YourByteVar]
pause 500
GOTO Main
END


Rx part

@ device HS_OSC, LVP_OFF
define OSC 20

DEFINE LCD_DREG PORTC 'LCD data port
DEFINE LCD_DBIT 0 'LCD data starting bit 0 or 4
DEFINE LCD_RSREG PORTB 'LCD register select port
DEFINE LCD_RSBIT 7 'LCD register select bit
DEFINE LCD_EREG PORTB 'LCD enable port
DEFINE LCD_EBIT 5 'LCD enable bit
DEFINE LCD_RWREG PORTB 'LCD read/write port
DEFINE LCD_RWBIT 6 'LCD read/write bit
DEFINE LCD_BITS 8 'LCD bus size 4 or 8
DEFINE LCD_LINES 2 'Number lines on LCD
DEFINE LCD_COMMANDUS 2000 'Command delay time in us
DEFINE LCD_DATAUS 50 'Data delay time in us

TRISC = %00000000 'Set port B as output
TRISB = %00000000 'Set port D as output
low PORTB.6 'Set the R/W bit to low

pause 1000 'wait until the LCD initializes

INCLUDE "modedefs.bas"
ReciverPIN VAR PORTA.0
ADCON1 = 7 ' Alla digitala
YourByteVar var byte


pause 100
LCDOUT $FE,1, " Receiving Bus ID"

Main:
SERIN ReciverPIN,T2400,["~"],YourByteVar
GOSUB LCD
GOTO Main

LCD:
LCDOUT $FE,1
Lcdout $FE,$C0,"BUS",DEC2 YourByteVar
PAUSE 500
RETURN

END