2 or 5 Hz Base Transmission

[sek-surveyor]

Very interesting discussion. I have just recently changed our Triumph 2/LS Combo to beast mode. I haven't had a chance to utilize it in the field, but it works great and is impressive in our parking lot.

The question that I have that relates to this discussion has to do with the FCC guidelines. I am pretty sure that per the link below, that the FCC allows for:
https://transition.fcc.gov/pshs/public-safety-spectrum/narrowbanding-faq.html#question_2_2
Any of the following meet the 12.5 kHz equivalent efficiency requirement:

• One voice path in a 12.5 kHz channel
• Two voice paths in a 25 kHz channel
• Data operations on channels greater than 12.5 KHz must employ data rates greater than 4.8 kbps per 6.25 kHz channel, such as 19.2 kbps per 25 kHz channel

I noticed an ealier post that showed (if I am reading it correctly) that the baud rate for D16QAM at 25kHz channel spacing is transmitting at 38.4 kbps. Doesn't that meet the FCC requirements? My radio range dropped off drastically when I changed to the 12kHZ channel spacing on our old unit. Am I wrong to assume that better radio range can be achieved using the 25kHz channel spacing?

Thanks,
DR

 

[Donald E Robinson]

I got the Beast running smoothly except for one thing. When starting Staking mode, it alternates from "Stand Alone" to "Fixed" very rapidly. To get this to stop I have to select the Engine Screen (upper left corner) and then ESC to return.

At the end of the day the FIX deteriorated, but, I assume it was due to the drain on the battery because it took a long time to recharge it. I was surprised to find that the radio was barely warm (running at 4watts all day).

I think Javad needs to fix the mentioned bug in staking mode.

 

[Shawn Billings]

Don,
Are you certain that it alternates between Fix and Standalone rapidly or is it possible that you are seeing it switch from Fix to Float rapidly?

If it is alternating between Fix and Float rapidly, this is likely because verify with V6 resets is turned on. With Verify with V6 Resets turned on, the receiver will intentionally lose lock for a user specified number of times. This is referred to as "Phase 1". Once the receiver has passed Phase 1, the engines are allowed to keep the fix through "Phase 2" also referred to as the "Smoothing Phase". This phase runs until the number of epochs and consistency level have been reached. The third Phase is relatively new - Validation. Validation resets all engines one last time at the end of collection and collect 10 additional epochs. Phase 1 ("verification") and Phase 3 ("validation") are meant to check the fix the receiver is using to make sure it is correct. Each will cause the receiver to intentionally lose the fix showing Fix and then Float at the start and end of each shot if turned on.

This video is somewhat long, but it shows the verification process and describes it in detail.

 

[Matt Johnson]

Very interesting discussion. I have just recently changed our Triumph 2/LS Combo to beast mode. I haven't had a chance to utilize it in the field, but it works great and is impressive in our parking lot.

The question that I have that relates to this discussion has to do with the FCC guidelines. I am pretty sure that per the link below, that the FCC allows for:
https://transition.fcc.gov/pshs/public-safety-spectrum/narrowbanding-faq.html#question_2_2
Any of the following meet the 12.5 kHz equivalent efficiency requirement:

• One voice path in a 12.5 kHz channel
• Two voice paths in a 25 kHz channel
• Data operations on channels greater than 12.5 KHz must employ data rates greater than 4.8 kbps per 6.25 kHz channel, such as 19.2 kbps per 25 kHz channel

I noticed an ealier post that showed (if I am reading it correctly) that the baud rate for D16QAM at 25kHz channel spacing is transmitting at 38.4 kbps. Doesn't that meet the FCC requirements? My radio range dropped off drastically when I changed to the 12kHZ channel spacing on our old unit. Am I wrong to assume that better radio range can be achieved using the 25kHz channel spacing?

Thanks,
DR

We are working on trying to get FCC licenses with 25 kHz channel spacing. 12.5 kHz channel spacing limits the modulation that can be used to D16QAM. With 25 kHz channel spacing DQPSK modulation could be used. Field test have found that D16QAM modulation decreases the working range of the radio approximately 20% as compared to DQPSK modulation.

 

[Donald E Robinson]

Shawn,
I believe you are correct. Fix to Float. So, if I just turn off verify during staking mode this should work. OK Thanks! I'll watch your video tomorrow.

 

[Jim Campi]

Very interesting discussion. I have just recently changed our Triumph 2/LS Combo to beast mode. I haven't had a chance to utilize it in the field, but it works great and is impressive in our parking lot.

The question that I have that relates to this discussion has to do with the FCC guidelines. I am pretty sure that per the link below, that the FCC allows for:
https://transition.fcc.gov/pshs/public-safety-spectrum/narrowbanding-faq.html#question_2_2
Any of the following meet the 12.5 kHz equivalent efficiency requirement:

• One voice path in a 12.5 kHz channel
• Two voice paths in a 25 kHz channel
• Data operations on channels greater than 12.5 KHz must employ data rates greater than 4.8 kbps per 6.25 kHz channel, such as 19.2 kbps per 25 kHz channel

I noticed an ealier post that showed (if I am reading it correctly) that the baud rate for D16QAM at 25kHz channel spacing is transmitting at 38.4 kbps. Doesn't that meet the FCC requirements? My radio range dropped off drastically when I changed to the 12kHZ channel spacing on our old unit. Am I wrong to assume that better radio range can be achieved using the 25kHz channel spacing?

Thanks,
DR

Hi DR,

I could be completely mistaken on this point however; I believe the FCC requires that we show NOT the theoretical maximum transmission rate of the radio, but rather the actual, minimum transmission rate at a given frequency bandwidth for our application.

The data transmission rate at 1 Hz vs 5 Hz (beast mode) is not the same. Our radios will theoretically transmit 38.4 kbps at 25 kHz with D16QAM modulation. To meet the equivalent efficiency requirement, we would be required to show that our systems transmits at least 19.2 kbps at 25 kHz. My understanding is that a base transmission rate of 5 Hz could be just below that minimum.

It also appears that Matt is saying that a modulation of D16QAM decreases range slightly.

As soon as the upgrade was released, it was obvious that a higher base update rate dramatically increased field efficiency. This led me ask about a 10 Hz (or higher) update rates. To make that happen, I was told modifications to the processor as well as increased channel spacing is required.

Hopefully Javad is testing the wider channel spacing to accommodate the Triumph CPU's higher processing capability - allowing for base update rates in excess of 5 Hz...

It won't be long and we will achieve a highly confident/consistent, 6 engine verify w/ reset in a few seconds.

 

[Donald E Robinson]

Would there be a problem resetting the transmission rate from 5 Hz to 10Hz, during a survey in progress, to obtain optimal UHF range. (i.e. tying to a distant NGS monument in order to apply the "Shift" to the autonomous base station)?

 

[Shawn Billings]

No I don't believe you would have any problem with this Don. You'll have to stop the base to change the transmission period from 1 (1Hz) to 0.2 (5Hz). But once you perform the shift, the base point will be stored and you should be able to recall the base, as shifted, to start the base again. The shift will stop after you stop base on the 1 Hz session, but the base point stored in the database should be the shifted position. When you set the base up for 5Hz, recall the base point from list.

 

[Nate The Surveyor]

I've been meddling a bit with my antennas. I have an old old 4500. It is a radio, for the rover, that is a part of the old modular system. Ie, the rover is in many pieces. And connected with wires. The radio hangs on a brackett, to the side of the antenna. Well, I took this brackett, paired it with my old transmitter antenna base, and wired it with an adapter to the LS. So, now the LS has a brackett, and a 1/2 wave antenna, attached to the side.
The base has a 5/8 antenna. I have had radio problems, in hilly, thick timber, getting consistent, signal, And this allowed me to keep working the last few days.
In this environment, I'm thinking of going back to a 1/2 wave antenna, at me base transmitter.
I also have bought a yagi, with wire, and adapter, to put at the base transmitter, or on the rover, just for this sort of thing.
I'm not knowledgeable about radios. So long as things are working, you don't have to learn... But I am trying everything....
A more direct way to say my point is: Maybe a larger external antenna, to collect more signal, for that long shot, would work for you, and be less cumbersome, than switching hz rates, at the base.
I have not yet had a chance to try the yagi, at either end yet.... But the 1/2 wave at the rover saved my day yesterday.

 

[Adam]

Would there be a problem resetting the transmission rate from 5 Hz to 10Hz, during a survey in progress, to obtain optimal UHF range. (i.e. tying to a distant NGS monument in order to apply the "Shift" to the autonomous base station)?

Don, do you have a rtn network available, I swap between the radio and the network quite frequently for the same reason. That is if one is available, if one is not available, but cell service is then a TCP works great and you can still run at 5hz, The state network here is only putting out 1hz. Once your base is set, you can swap between the rtn, tcp, or radio profile without having to go back to the base too.

 

[Donald E Robinson]

Adam, RTN is available, but, I have not purchased the service nor do I want to add additional phone service. That is why I bought the UHF.

 

[Adam]

Don, You will like the new DPOS for rover points when it gets released. You will be able to go get that out of range monument and process it via DPOS.

 

[Donald E Robinson]

Thanks for the update, Adam!