Facing problem in RF transmission

I programmed 89c51 controller to keep on transmitting 20 characters in 2 second interval "33333333333333333333" the tx of the controller is connected with the rf transmitter input while debugging the rf transmitter 20 characters are displayed in the p.c.

In the recivier end I connected rf recivier and max232 to display the data in the p.c.

The data is reciving in the recivier end but some junk errors (characters) are generating ( i attached the capture file below)

Is there is any way to filter the junks.

Please suggest me the result

If the attachment is not opening scroll down to find the pdf file attachment.


Thank you.

Couldn't open the doc.

But if you have noise problems check that the capacitors being used have a resonance at the frequency of the RF.

send several(10) of 0x55 at start of data sending .

If its conformed that the problem is with RF, Simply use a Bandpass filter with center frequency at your operating (RF)frequency and attenuation at the noise frequency.By using simple L,C combination.

hi
i am also working on the same type of project
mean i programmed the 892051 to transmitt the 5 chracter and
its checksum byte that is calculated befor transmission
and send it to the serial buffer ,892051 is directly conected
to the TX unit (RTF3) of www.okwelectronics.com that is use the frequency 433.92M
for rf transmission etc ..
and on the reciever side iam uisng the RRF1 unit of www.okwelectronics.com
that is directly conectd to TX pin of 892051 .and RX pin 892051 is connected to
the Max232 to monitoring the recieved packet on hyper terminal
but thier is n packet rxd ...if we directly conect the TX pin Of TX 892051
to the RX pin 892051 ,it will work perfectly but when i involved the TX RX module
i am fail to understand what is going wrong with this .............
but anyway i will continue my strugle to trace out the problem ..
and livingston ur uploaded file dosnt open can u upload it as pdf

and i also want to know what happend about ur problem
according to my opinion if u follow the header & CRC technique, then ur problem will be solved

Hai halee awan,

Now my problem solved the problem is in anteena,

I attached the capture file in pdf format find it

thanks for ur reply but Livingston in which formate u r upload the pdf it is not in english language .. and iam still waitng for watching ur cct daigrame and other

When rf recivier is connected some junks came in the hyper terminal that is not the language to read, that is junk.

ok thanks
can u send me ur project cct diagrame and what was the problem in antenna
today i have test my TX & RX unit ....but Livingston iam facing a starnge problem
when i conect TX directly to RX it works
but wireless it dosnt work nothing apear on hypert terminal
i will upload complet cct daigrame later

First you upload your circuit diagram
and, Are you doing in dot board? how you connected the components by wire or drawing a track by lead?

here is the complete detail about my project
it include Schematics, PCB, diagrame and code

Hai halee awan,
I saw your code as well as your pdf nice, there is no problem in your code,

I want to know some thing about your project as follows,

a) How you connected (in the transmitter end) the tx of the controller and data in of the rf transmitter ? You connected the two points with wire or ?...(you made a track by soldering lead itself).

b) As same as in the receiver end also (between data out of the rf receiver and rx pin of the controller).

c) What type of anteena you using in both the end's,

Added after 38 minutes:

Have a look at this type of rf module also it is quite good.

Frequency is 433mhz as same as your module
It's the product of radiometrix.

Hi Thank Buddy

Has the problem solved

thanks a lot!

hi livingston
here is the ANS of ur Q and now i am stuffing new on wire bord ..
1-yes it is pcb made track
2-and on the reciever end there is also track not wire conection
3-antenna type ?---i am using wipe (vertical)Antenna adjustable legnth about 17cm-1.5Ft
and i also have Q about ur TX2,RX2 module
how much its price (both pair) and how i can found it or buy it as living in pakistan
and is there any facility for students or anyone to get a sample of it
ok waitng

Radiometrix rf module cost's - one transmitter cost's 800 rs.
One receivier costs 950 rs.

no sample piece you can get, and buddy i want to see the data's what you getting in the receivier end?

This type of anteena is what i am using it is recommended one.

hi livingston thx for reply
and what mean 900rs ( currency)
and i will used this project to monitor the air parameter that will Transmitt by the my own made RC plane
okkkkkkkkkkkk

Hai halee awan,

Rs is nothing but (inr)- rupees,
Yes radiometrix will appropriate for your project

thx livingston
livingston if i want to purchase that pair(UHF FM Data Transmitter and Receiver Modules) radiometrix then could u help me to purcahse it if yes then inform me how it would be done ....and can u like to upload ur made project detail i want to see it what u have done okkkkkk