Serin Serout possible wiring distance

[Ioannis]

Very impressive range. Can you give us your antenna calculations?

I just have succesfully tested a pair of Adeunis ARF7761 modules at 169MHz@500mW that covered over 12Km range. One side used a 42cm l/4 atached on a short RG58 cable and the other a dipole l/4.

Ioannis

[tasmod]

Hi Ioannis,

I used Yagi Calculator software from here. It's a simple to use but excellent piece of software.
Yagi has 9.8dbd gain.

The Moxon Loop also has design software available but I've now changed my mind re the loop as it is hard to make it rigid enough for the application. Loop has 3dbd gain.

There is of course the frequency difference losses between our module setups but that's pretty impressive range.

I estimate that line of sight and two yagis will do 12km as well with these units. It's not out of the way to setup two long yagis of say 21 elements 15.5dbd gain each to achieve more range at fixed locations.

In my use this will be a portable setup. It needs to be erected and taken down quite easily and to maybe signal penetrate a bit of bush. This at much closer range of course.

I'm currently building the finished yagi in plumbers 15mm copper pipe as the boom and 4mm brake pipe as the elements. Easy to solder in and to bend the dipole out of. It will be used in vertical polarisation as the 'receive' end will be a small vertical colinear with small gain.

Software for signal strength for setup of yagis is in progress. This is what I have so far in progress and have posted a question re syntax in Ciseco forum.

I need to work out the lowest values for sigfield/sigcontrol variables , highest value (lowest signal) is around 88-90 as a returned value. Then send to lcd display.

rssion:

    SEROUT2 PortA.3,84,["BOB",sigon]    ; puts slave module in test mode via code
    
    PAUSE 1000                                    ; wait 1 second
    SEROUT2 PortA.3,84,["+++"]           ; send guard character
    PAUSE 1000                                    ; wait 1 second
    SEROUT2 PortA.3,84,["ATNT3"]         ; place unit in test mode
    SEROUT2 PortA.3,84,["ATWR"]          ; write to memory
    SEROUT2 PortA.3,84,["ATDN"]          ; exit command mode
    
sigstrength:    
    SERIN2 PortA.2,84,1000,sigstrength,[WAIT("aSSRSSIS-",sigfield)]       ; get slave sig strength value
    SERIN2 PortA.2,84,1000,sigstrength,[WAIT("aMMRSSIM-",sigcontrol)]  ; get control sig strength value
    IF jump = 0 then rssioff                                                                     ; check input to reset to serial
    GOTO sigstrength
         
rssioff:
    PAUSE 1000                                    ; wait 1 second
    SEROUT2 PortA.3,84,["+++"]            ; send guard character
    PAUSE 1000                                     ; wait 1 second
    SEROUT2 PortA.3,84,["ATNT0"]          ; place unit in serial mode
    SEROUT2 PortA.3,84,["ATWR"]
    SEROUT2 PortA.3,84,["ATDN"]
    GOTO main

[Ioannis]

Thanks for sharing. Regarding the serial communication, can you use the hardware serial port of the controller?

The I would suggest to use also the Hserin and wait for the response from the RF module instead of just PAUSE 1000. You can't be sure that the module responded in-time.

Ioannis

[tasmod]

Hi Ioannis,

The pause 1000 is the 1 second no input then the +++ and then no input for 1 second. This is the format required to put the rf module into 'test' mode for RSSI output.

Rob

[Ioannis]

OK, I do not disagree. But when the module enters the AT command mode by +++, doesn't reply with some kind of acknowledge? An OK or something?

I am on a slow internet connection now and cannot download the data sheet of the module.

Ioannis

[tasmod]

You are right it does do an "OK" back but after the one second of no activity.

To be honest so far I've ignored it in the software as it is only just about to be tested for real.

I appreciate your help. I should do a WAIT in there.

Rob

[Ioannis]

I'd prefer to do this in hardware serial port because it is much faster. Or at least the Debug and Debugin.

Some serial devices do respond very fast and had a case where Serin/Serout was unable to follow.

Ioannis