TRW-24G range problems !!

Wireless & IoT
1

Hello everyone,

I recently started to work on the TRW-24G modules, and in two weeks of work Ive put them to work almost fine.

I started using 1 byte of data and also 1 byte of address to make the things simple at start (shockburst mode and 250kbps). The plan was to make a serial (232) to RF conversor, so each byte received on the usart was sent trought RF and vice versa.

Just like ive read here, using 1 byte of address allows bad packets to be received (even using 16bits CRC). But what most concerned me was some missing packets that Ive sent and I didnt received on the other side. And that was happening like 10 cm (4 inches) of distance between the modules. When I tried putting them farther, the packet loss was so big, like 90%. So I tried using 40 bits (all 5 bytes) address and for my surprised it also reduced drastically the number of packet loss (like zero in close range) and less than 1% within the same room. But if I take one of the modules for more than 4 meters away , the thing starts loosing packets again, and when there is a wall or something in front, also gets worse (as expected), but I think it is too close to miss so many data. I dont know if my circuitry is making too many noise, because Im working on a universal board with a couple of wires soldered, and using ATMEL 89C4051 (said to be very noisy). As power source Im using 12VDC regulated with a 7805 (for powering the max232) and using 3 diodes (1N4148) to drop the 5V to aproximately 2.6V (Ive tryed using only 2 diodes and put the TRW VCC to 3.4V, but it worked just the same) The atmel is also working in 2.6V (the communication beteew the max at 5V and the atmel at 2.6 is working fine, just a few more diodes).

As it is working just fine at very close distances, I think Im respecting all the timing in configuration and data transmission, but i dont know how to make the thing works at larger distances.

Ive already tought about making a protocol to ACK, and RESEND if needed, but that would work only for less than 10% of data loss.

Im now using the following configuration:

-Shockburst

-250Kbps

-Frequency 2.4 (configuration word 0)

-1 channel

-RF power 0db (config word 11)

-XO frequency 011 (althougth I dont really know witch crystal is there because of the metal cover ) default was that so I didnt change it

-CRC 16

-5 bytes address

-9 bytes data (that would be too much overhead to send only 1 byte of data with 5 bytes of adress)

Ive tryed using other channels (frequencies) but no result (sometimes worse)

Anyone have any clues?

Thanks,

Arthur

2

I’d highly recommend a real 3.3V Low-noise regulator. Diodes ain’t going to cut it with RF.

Crystal on the RF-24G is 16MHz (under the cover, there are pictures on the forum somewhere here).

Use 40-bit addressing.

And that’s all I can think of at the moment. Good luck with the RS232 trick. The original SMiRF was a pretty evil chunk of code. Which reminds me, we need to post info on the new nRF24L01 :wink:

-Nathan

3

I am use LM317 to 3.0V for TRW-24G,but how is the CE,CS,DATA,CLK1?

Other topic use the 1N4007,but I use 5V and 5 1N4007 my voltage meter will be 3.xV.If I use 3 1N4007 the meter will be 3.9V…

4

Hello,

I am new to this device (TRW-24G) as well. Should I know anything about this unit? In other words, are there any suprises that I should know about (for range or operation of the unit)?

I have wrote test code to communicate with this device using a PIC, however, I can not get it to work? Do you have sample code that I can look at besides what is on sparkfuns web site?

My voltage source is also a LM317 (3.0Volts). I also must use a Level-Shifter (5V to 3V) as my microcontroller is running at 5V. However, when scoping out the pins and data, everything looks fine at 3V level.

Any ideas or help would be appreciated???

Thanks,

Chris

5

Hello,

I now have the same problem as Arthur-- original question above. I can get the unit to work about 2 inches apart and then when I go to another room, I lose some packets (Data doesn’t match at all).

I am currently using a LM317 set for 3.0Vs… What can else can be wrong or what else can I do?

Thanks

6

I’m having trouble getting mine to work in also. I am also running MCU at 5V and using 3 diodes for each pin to drop the voltage.

Just curious, does anyone have a wiring diagram handy. Any file format is fine with me if you have one. I’m guessing you used transistors connected to each MCU pin to send regulated 3V to the TRW-24g?

7

sparky:
I’d highly recommend a real 3.3V Low-noise regulator. Diodes ain’t going to cut it with RF.

:stuck_out_tongue:

I got mine working just by taking Sparky’s suggestion and using a voltage regulator (I used 3V) instead of diodes.

THANKS Sparky! I didn’t know about the diodes causing too much RF noise. Can you explain why this is or point me somewhere to learn about this?

Thanks a million!

8

Still trying to learn why/how diodes cause RF noise. If anyone could explain, I’d be very grateful!

9

Pretty simple when you read about it. To “up mix” a signal from baseband to RF (taking 0-1MHz and shifting its frequency to 2400 to 2401MHz) needs a non linear electronic component. Guess what… diodes are non-linear! In fact, they’re still a component in basic radio transmitters today. Better ways have come along, but you can’t beat them for simplicity.

10

I’m also having range problems.

Every thing works fine when both TX and RX are on the same board. But when I try to TX from a distance things are really bad. I tried powering both the TX and the RX using batteries (less noise) but not much improvement.

I am TXing the same packet every 200ms. I observe the RX DR1 to see how things are going. I RX an average of 70% of the packets. This is @ 250Khz. @1Mhz it drops to about 50%.

When TX and RX are about 10cm apart on the same board I have about 100% success.

The distances I’m testing are about 3 to 4 meters. The specs talk about 100meters!!??

Ah btw, i tried changeing the power output and not much difference there either. Actuall @ 0db things are really much worse.

Any ideas?

Any ideas?

11

i am using MirF modules. Internally i think they are the same as RF24G.

once i lost the link the module would not get a lock on the signal again. so now i just reload all the config bytes into it and set it to recieve and it works fine.

just wanted to share my experiance.

take care

12

The RF-24G’s have what we hope are tuned square loop antennas. At best these give a 1-3dB boost vs true omnidirectional. Also, the range spec is from the manufacturer, not a tested range (like most of the in-house designs are).

Now, there’s a few things to consider. Are you in a room with lots of metal? Are the antennas on the same “plane” or did you attempt to aim the “loops” at the other (this is actually bad!)? Did you make a PCB or are you breadboarding?