• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

Decode GPS over P25.

Status
Not open for further replies.

atomicric

Member
Joined
May 1, 2020
Messages
14
I know that this has been discussed here before but with no real resolution. I was wondering if anyone had success in extracting GPS data from a P25 transmission (or even analog) from an APX radio? I am aware of the core upgrades required to make this work and don’t need info in that regard...basically looking for an alternate means to obtain this data and export it to something else.
 

Mr_Boh

Member
Joined
Oct 10, 2016
Messages
534
Location
The Land of Pleasant Living
As I discussed in the other thread, more often than not, it uses LRRP, which is defined by P25. You will want to read up on the protocol, it's basically XML. You are going to want to understand the implications of this protocol. One of the reasons you will want to is the subscriber needs to receive instructions about where and how often (cadence) it should send location updates. These updates are sent on seperate channels from voice. This is more often than not what the "data" is when you are monitoring a trunked system on tools like Unitrunker or DSD+.

DSD+ (and I think SDRTrunk) naively decodes this, and this is probably going to be your best bet since it will support conventional or trunked streams. But you are more or less stuck displaying it on their map. I don't know enough about SDRtrunk to know if it will do conventional as well, but I know it can display LRRP from subscribers on a trunked system.

If you are looking to learn about LoPTT (Location on PTT) and LoRX (Location on Receive), these are proprietary to Motorola. That's what you see when you have the direct PTT with another subscriber and you can see each other's locations. You don't want to put an IMW in your core? You may be on your own developing this since you would have to reverse engineer the protocol. A tip I can provide you though is you can use something like Wireshark to decode the data in transit as long as you have a way to feed it the IQ output of the receiver. You could use this information to then pipe it to an application. You would have to decode the data string from the subscriber because the location is embedded with the voice information.... hopefully you are starting to understand why people pay the money and time for the IMW, and why there are fees for the API, etc. LoRX requires TDMA so I am sure that's a whole special beast on its own trying to reverse engineer it.

EDIT: The other point I should have made about LRRP is because the device needs instructions, you will have to get some way to trigger it initially sending the updates. Another function of the IMW in a Motorola P25 core.
 
Last edited:
Status
Not open for further replies.
Top