Month: September 2013

I’ve managed to add functionality to the page to display they mobile phones GPS coordinates on the web page on the status page. I’ve also coded the status page to calculate a few interesting numbers.

1. The distance (Across the surface of the earth) from the user’s mobile phone to the HAB

2. The LOS from the users’s mobile phone to the HAB (i.e. we take into account the altitude)

3. The bearing  – (direction from the user’s mobile phone to the HAB).

Obviously, the user needs :-

* Use a mobile phone with GPS

* Have GPS enabled…not the WIFI as a means of locating itself

* Allow sharing of location with the browser

This information will be very important when we need to track the HAB! I’m pretty happy with that!

Progress has been slow in the radio link side of things. Testing of the new RFD-900 modems has been painful for a number of reasons.

1. They chew up a lot of power and go through a lot of batteries and I have a feeling that when the RFD-900 demands a lot of power, the batteries just cannot supply it.

2. There seems to be packet loss, and some very strange things occuring. I’ve been in contact with the supplier regarding this.

3. I SUSPECT there is some interference between the wifi and rfd-900…but there is a lot more work to do there.

So in short, I’m a long way from doing some long range tests and I’m probably going to need to purchase more batteries.

I purchased myself some 18650 batteries from China – 8 in total. For those who are unfamiliar with 1860 batteries, they are 18mm in diameter and 65mm long. They are Lithium Ion batteries with a voltage of 3.7 volts.

These batteries fit in a battery box that fits VERY snugly in the main Electronics box. Alas…on the first test, the batteries failed after 30min of operation. It turned out that one of the batteries died – collapsed. This apparently happens if too much current is drained from these batteries, or they are charged with a charger in a ‘bad’ (over voltage?) way. That is apparently why most 18650 incorporate a circuit protector to stop this from happening. (When they have this circuit protector added…they are typically a few more mm longer).

I suspect I’ll need to invest in more expensive (non-China 18650 batteries).