T2 and 1 Watt UHF Radio/Antenna on Same Tripod

[Jim Campi]

Do you see any theoretical problems with this configuration?

Bracket adds about 1 mm to the total height of the T2.

At 980 feet I had excellent UHF service using the LS internal antenna.

For small sites it increases productivity by reducing the amount of equpment to carry set-up and take down etc, etc.

 

[Matt Johnson]

I don't see any problems with using that configuration for small sites.

 

[Grant Nevill]

Jim, Matt, all-

What has been your experience with the internal battery life for the 401BT? I used the 401 in the summer and was able to get about 6 hours at full 1 watt output, while the other day in mid 30 degree weather had about 4.5 hours until the unit ran out of power. It seems the SAE connector for charging could also be connected to a 12v battery to extend the transmit time.

Jim- I have found that with about a 4'-5' radio height with reasonably flat terrain (20'+/-vertical relief) in residential / commercial areas where the buildings do not exceed three stories the LS can get to 3500' with the external antenna. In order to get a better distances I would probably need to raise the radio or get an extension for the antenna.

We currently use a 35 watt radio with our other GPS system and for me it looks like the 435 might be a best solution in order to get the 5000'+ range we need in hilly terrain (100'+vertical relief) or in more urban areas.

 

[Jim Campi]

Hi Grant,

My surveying work is an adjunct to engineering. I typically survey about 10 days per month with a maximum survey duration of 4-5 hours. In almost every case I use a base rover set-up and always transmit at 1 watt. In the last several months using the equipment, I have never seen the radio's battery drop into the yellow range. I typically recharge after about 4 hours of continuous use.

When I first bought the equipment I attempted a 10,000 ft baseline using supplied antenna in flat terrain. No dice. I haven't tried with an upgraded antenna.

I'm fairly new to GNSS surveying, however my best guess is that you are a candidate for the 35 watt radio based on terrain and range.

 

[Shawn Billings]

That 3500 foot range sounds believable, but maybe on the low side. With the 4 watt radio I get 7000-8000 feet. This follows an inverse square pattern. Quadruple the power, double the range. 35 watts should yield about 6 times the range of the 1 watt. Of course as with all things, it depends.

 

[Matt Johnson]

The data sheet specifies the typical batter life of the HPT401BT to be 6 hours. I haven't used it when it is cold to see how much of a difference there is. I have a HPT435BT that I use now but still also have the HPT401BT.

You could connect the HPT401BT to the Battery KIT 1 with the "Power Cable, DB15/SAE (0.3m)" that comes with HPT404BT:

I don't see it listed to order in the accessories but if you wanted to order it someone could add it to your order.