Hello,
I am having a limited range issue (about 5m) when testing two pairs of HC-12's indoors.
The two test rigs work ok in same room, but thru two brick walls loopback is data has many dropouts. I have checked the reports and fixes for Bad Clones and I think I have good HC-12's
As they have the www.hc01.com logo on the back and the miss clone tracks are not missing on these boards.
My test rig is as follows:
Two HC-12's are mounted on a breadboard side by side powered and driven by a nano.
The only AT command change I have made is that two of them are Ch1 and two of them are Ch50.
Hence they are all 9600 bps, max power, FU3.
On breadboard One; I have the Nano and a Ch1 HC-12 that transmits a text message from the nano and a ch50 HC-12 that's output goes to my scope and logic analyzer. (So Two HC-12 side by side a Ch1 and a Ch50)
On breadboard Two; I a have a pair of HC-12's one is Ch1 and the other is Ch50 these are crossover connected Rx to Tx and only have power from a power bank.
So this little system works as follows: breadboard One ch1 HC-12 transmits a message that is received by the ch1 HC-12 on breadboard Two. This breadboard Two ch1 HC-12 loops back the received message and passes it to the ch50 HC-12 on breadboard Two via a RX to TX link wire.
The message is then sent back to breadboard One over ch50.
This loopback works fine in same room as I can monitor data sent and received on Breadboard One with my scope and logic analyzer. However if I move breadboard Two into the next room I get lots of broken packets received back at Breadboard One.
Any thoughts, Bad Clones that look like and seem to be good HC-12's or a ch1 next to a ch50 HC12 interfering with each other. Any one else tried full duplex comms with two pairs of HC-12s?
Many thanks in advance imk
Yes, see pic, Breadboard One is on left and Breadboard Two is on Right
Breadboard Two HC-12's are powered only from the STM nano but are Not serial connected to it, just looped HC-12 Tx to Rx.
The solution works within this room, but two brick walls and many lost packets, Tx msg below:
Serial1.println( "G1xxG2xxG3xxG4xxG5xxG6xxG7xxG8xxG9xxM0SxxM1SxxM02xxM3Sxx");
I put Breadboard Two at back of garage 20m or so away and no data is returned, steel door and four brick walls.
Problem I am having is this normal behavior or bad clone HC-12.
Did the calculation. Channel 1 is 433.4mHz and channel 50 is 433.6mHz, so not so far apart in percents. One transmitter will absolutely jam the adjacent receiver.
Many thanks for the posts,
Sorry for late replay, been out helping at local observatory.
According to HC-12 documentation each channel is 400khz so ch 1 to ch 50 is 50x400khz=20mhz
I thought that would have been enough, tomorrow I'll set them to ch1 and ch100 for maximum Hz separation. thanks again IMK
Sorry, misread the value. But the frequency is NOT the problem. It's the physical closeness of the antennas. If you separated them by 15 feet or so it might work.
paulpaulson & Paul_KD7HB
Thanks you soo much for the replies and I think there is a element of truth in both of your suggestions, aerials to close and too small both fit the conditions.
Where I am perplexed is that the solution work in the same room so why are close aerials not a problem in that situation and become a problem when the breadboards five meters apart. Also why does the solution not work at all when in my garage to house thru four brick wall suggests HC-12 low power clones. I am going to test the solution outside to see if any better. Also I am going to put little app at each end to ping pong back and forth a message so the system runs half duplex not full duplex to see if it is a pair of simultaneous that cause the problem. I'll be back Thanks again imk
Hello,
So just to close out this thread, the problem is simple.
The HC-12's that I have don't like being 25mm apart when one is receiving and other is transmitting.
The testing: I removed the two ch50 HC-12 from the breadboards.
Put the Rx'ing one my desk and plugged it into my logic analyzer and set it recording for and hour.
I put the Tx'ing breadboard with power bank in my backpack and went for walk up and down my road. It turns out they have a One Indoors One Outdoors range of about 100m, and have at least a 10m range indoor thru several brick wall when only one HC-12 is Tx'ing. If a second HC-12 Tx'ing even on a 50 channel steps away it clobbers the Rx'ing HC-12. I guess the Rx'ing one AGC (Automatic Gain Control) steps in and basically reduces the Rx gain so much that it can only Rx data from a same channel HC-12 a couple of meters away. Hence my HC-12 Full Duplex experiment is a failure. I have bit of code to write to see how good there are when used in Half Duplex, but I suspect they will perform similarly to the simplex testing I did above.
IMK
Thanks again imk