Yes can be done,I done it
Zello via comms ports
FRN Via comms port
NO VOX avoid like plague!
Add lag to system
Use busy LED or mute pin inside CB to control COS signal from radio to RS232 comms port CTS (set activate hi or low depending on logic level of Mute\Busy voltage) ,best used with a opto isolator
Use a opto Isolator to control PTT to radio using RTS activate hi
Hint for CB tap of speaker audio,use a 8ohm resistor load and 1K resistor then to tap off audio,very important as using the external speaker socket
it needs to see a proper load,the resistor being that load ie a speaker!
Feed AF signal thru a audio transformer to isolate PC ground from Radio ground
Terminate the PC side LINE IN\OUT with a 100-150R ohm resistor,this prevent noise on leads.
Adjust CB volume using another cb for around 75% level on sound card input LINE IN
Use a 1khz Wav sample loop to set up TX side again around 60-70% from sound card
to test your interface use this simple software.
Micro ridge RS232 tester https://www.microridge.com/comtestserial.htm
it will feed a 1khz test tone into your cb to check deviation
I found 50-100mV (RMS) for 60% modulation was rule of thumb into the LINE IN\OUT sockets of PC sound cards for best S\Noise,needs to see from CB radio.
I would also suggest set the FM squelch to S-5 signal as anything less than that is just to noisy
it may sound complicated but its not,just do each step a bit at a time
the hardest part is probably finding the Busy signal generally 0V=Busy 5-8Volts Not Busy,but can be inverted.
best place to find it signal is Busy LED or Mute pin on audio amplifier
this signal drives the RS232 to tell system its seeing a valid signal from CB
it works 200% better than VOX
IF you have a deviation meter and a RF signal generator,it makes that task sooo much easier on first one,but even with thats,as long as have a second cb radio to act as the mobile,and set on bench as the gateway u can get levels to sound right.I found say 5555555 and adjust PC sound card slider for around 75% on bar levels was about right.
Peak fm deviation was around 2.0khz no more using ETSI spec current equipment (not MPT1320 UK)
Once you done a couple its really easy.
F6DQM Simplex repeater
all worked fab on cb
One more note,if doing CB gateways or CB meshed networks the one thing to really consider is the use of CTCSS decode on the base gateway,i think this is really important to help protect gateway from QRM,27mhz skip and busrt noise open the squelch line up,causing havoc.
I think this is part of the reason why some go wrong .
With new cb coming out 2019 with CTCSS i can see ROIP becoming quite popular and practical
From experiments done on 3 cb gateway built so far CTCSS was vital I found to make it practical FM was best option,but did try Am mode and that did work too but lacks CTCSS.
But u can retro fit CTCSS encoders to your CB mobiles\hand-portable very easily,but new sets will make this a lot easier having CTCSS feature built in.
I know theres a new GPE Randy III handportable due,this does has CTCSS
CRT do cb cb with CTCSS and DTMF control access microphone
So if your real determined ,like I was,wanted to show the negatives out there,YES it can be done,BUT you will need certain skills to modify the radio and build the interfaces,test kit to check levels correct.
It also does not stop there..either! if you want a successful and 100% reliable system
You got to consider your site location..its no good placing it at your home QTH is operating cb as well,thats one thing I learnt!
Otherwise your gateway will be on and off due to QRM on your other cb in house,it must be place in a RF quiet noise-floor location on 27mhz,that can be difficult in itself.
You must have either a 4G router or wired internet access on your planned site,dont use wifi (another mistake commonly made) it slows and lags system
The PC machine must be 100% reliable on 24\7 and have cooling ,the operating system must be stripped to basics and dedicated just for ROIP use,dont use your home machine as its cluttered up with all sorts!
I did find mini Intel PC will work well and can run 24\7 but consider heat and internal environment of your site,does it over heat,can heat dissipate easy,does it get too cold on site!
these things are very important to consider when getting into this on a reliability scale.
Cooling fans on your CB radio if gateway very Busy have to be considered in the design, and duty cycle of the power supply system.
Mains-fail back up for PC\gateway\Router-also has to be considered and any alarms to indicated a fault-Big UPS
and lastly ensure you have a Time out timer on CB,either thru the software gateway,internally of external hardware so in an event something goes down,the the CB is not stuck permanent in Transmit mode!
Yes I had that happen and it nearly cooked my cb radio,oversight!
So there's my experience of CB ROIP,YES it can be done,Yes it does work well,Yes you can mesh up to PMR446 & Network radios too....
BUT.. To do this you going to need at least some extra pair of hands to help out initially,do it cheap and nasty it will fail or be at best okish,do it right and put time and effort in ,it work fab,reliable and very practical.
I would say this is for the beginner,but maybe best suited as a group venture as ull need help in other departments not just the electronics.
Take each step bit by bit.
Take some time to consider before building a CB gateway
have i got the resources?
a site with electrics,internet and a place to mount a mast and antenna system?
electronics and soldering skills?
Can read or understand CB radios schematics or where i need to tap signals off?
Who or what interface im i going to use?PCB skills can be very handy ?
Do i need to bring in more skilled people to make this succeed?
Antenna System hardware,coax,brackets,and equipment to fit the antenna mast?
Im not trying to put people off,but I think ROIP on CB is very new concept and because CB radios do not have an easy interface port purpose designed ready for this role it could present certain challenges.
And the site installation work to maintain your CB gateway can\could also present challenges if you want a reliable service from it and not having constant issues and problems with it.
But once you have done one and taken notes or Dos & Donts it will become easier as ull form your own rule book manual,like I have done.
Im personally holding off a 100% operational one,till i get hands on new CB due out mid year 2019 with CTCSS decoder built in,by then then hopefully the new President Electronics Randy III hand-portable will be out which will be ideal for CB ROIP use,plus I know new models due soon,that support CTCSS functions built in.
In mean time i continued to experiment and build up equipment needed for the site installation work,and racking up CB gateways into 19"rack enclosures,takes time and money im afraid like most thing in life!
All the best def have a go,dont be put off by the negatives!
Just need determination and a will to do it.
I will do an update once i have new CB (CTCSS model) kit in my hands,ive had software modified for me from china specially for this job.
Early days yet for CB ROIP
Rob P 73'