Joint license for the same radio frequencies

Thread Starter

brentclaas

Joined Sep 3, 2019
2
Hi

I am a stock market analyst from Belgium.
I am analyzing a stolen vehicle recovery company listed on the Nasdaq stock market.

The company uses terrestrial network triangulation. The signals are transmitted from the end-unit in the vehicle to a network of base stations. Additionally, since the primary application of terrestrial network triangulation systems in the telematics industry is vehicle location and not continuous two-way communication, short bursts of data are sufficient for tracking purposes.
These base stations send a radio frequency in the range of 966 - 968 Mhz. The use of radio frequencies are licensed and renewed periodically from the Ministry of Communications. Some of these licenses are designated as a “joint” license, allowing the government to grant third parties a license to use the same frequencies.

I have the following questions?
Is it possible for a competitor to use the same frequencies in the same geographical location or would there be problems with interference?

Thank you in advance.
 

SamR

Joined Mar 19, 2019
1,139
Signal triangulation is passive so the interference would come from trying to triangulate and differentiate multiple signals close to each other on the same frequency. So yes they would interfere. Optimally the signal would only transmit when triggered and not at all times. If the transmitter is operating in burst mode is it sending actual GPS location Data or merely a locator signal?
 

Thread Starter

brentclaas

Joined Sep 3, 2019
2
Hi SamR

The signal is only transmitted when triggered. Could a competitor use "Frequency Hopping spread spectrum technology" to prevent interference?
To answer your question: the company uses 3 main components:

SMART: a portable transmitter installed in vehicles that sends a signal to the base site, enabling the location of vehicles, equipment or an individual

Base Site: a radio receiver, which includes a processor and a data computation unit to collect and send data to and from transponders and send that data to control centers as part of the terrestrial infrastructure of the location system;

Control Center: a center consisting of software used to collect data from various base sites, conduct location calculations and transmit location data to various customers and law enforcement agencies;
 

SamR

Joined Mar 19, 2019
1,139
Doesn't sound like triangulation. Sounds like Cell Communication from an addressed device when activated with multiple receiving stations (cell/rcvr towers) spread over a geographic area to ensure wide coverage area. Much more resistant to interference than homing in on a xmtr signal and triangulating from 3 rcvrs to determine geographical location. Sounds like a LoJack system? If it's not actually xmting GPS location data it is measuring signal strength from several rcvrs to calculate probable location. Actual steerable antennas from 3 locations (triangulation) determines the heading of a xmtr signal from each rcvr antenna and plots to locate the intersection of the 3 signals. Which is pretty accurate and was used to locate lost boats transmitting VHF radio before marine GPS became the norm.
 

Externet

Joined Nov 29, 2005
1,410
If the mobile unit transmits the data of its built-in GPS receiver + the identifier for the vehicle, the central receiver could log and track all mobile units on a single frequency. Transmissions coinciding in time that may interfere to each other could be discerned/updated the next transmission.
If the mobile units have also a receiver built-in; can be polled/triggered to update reporting in turns.
 

DickCappels

Joined Aug 21, 2008
5,877
In answer to your question: Yes if the ministry permits it. Since signals are in short bursts and presumably carry identifying information interference is unlikely to be a problem.
 

Yaakov

Joined Jan 27, 2019
1,536
The answer to your question is entirely based in channel capacity. Yours is a complex problem since the vehicles will rarely be able to hear each other, and probably won't even listen, to avoid "collisions" (interfering with each other). The base stations will hear the vehicles, and sometimes, if there are enough of them active, one or more of the three will hear interfering stations when the others don't.

If frequency hopping technology is employed, it will reduce the likelihood of destructive collisions, but in the end, the channel has a particular capacity for active stations that will depend on the protocol used to report, the geographical distribution of the reporting vehicles and the terrain.

The bottom line is that shared use is not an issue, but channel capacity, by any number of users (even one) will be finite and specific. In this case we really don't care how many services use the frequencies, only the number of subscribers and the robustness of the protocol.
 
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