Telstra CDMA Rural Field Trial
"Mt Dowe" Base Station, NSW
Overview
This report outlines the results of several tests that were conducted from the Mt Dowe base station in Northern NSW.
The objectives of the tests were twofold:
Mt Dowe is a very high mountain top with an analogue base station situated 37 km east of Narrabri in northern NSW, and typically provides vehicle based analogue coverage across wide areas, with distances in excess of 100 km from the base station.
Mt Dowe
Mt Dowe is one of the mountains in the Mt Kaputar National Park, and is approximately 1500 m above sea level with a mean height of 1300 metres above the surrounding terrain, which is mostly flat with occasional bushland. Cotton farming is common in the area, with vast tracts of cleared land devoted to this activity.
Viewed from the West, North and South, the Mt Kaputar Range clearly dominates the surrounding landscape.
The Mt Dowe analogue base station is configured with high power 50 Watt transmitters and Omni directional antennas. This type of analogue configuration is common in many locations around Australia.
The CDMA installation is co-located and shares the same tower structure with analogue, is equipped with the Nortel "Boomer Cell", and configured as follows:
Test Methodology
For the purpose of assessing comparative analogue and CDMA coverage, two drive routes were selected extending westward from Mt Dowe.
Calls were established some distance inside the edge of coverage. The vehicles were then driven away from the base station whilst monitoring call quality at both ends until the calls dropped and could not be re-established.
Four wheel drive vehicles were used for the surveys, and fitted with:
Additionally a number of handheld calls were made with a CDMA hand portable outside the vehicle on the side of the road.
Results and Observations
Test Route 1 – Narrabri to Pilliga via Wee Waa
This test commenced by establishing a CDMA and analogue call in the car when leaving Narrabri (37 km from Mt Dowe base station), following a route through Wee Waa, and then on an unsealed road through to Pilliga (120 km from Mt Dowe).
Up to Wee Waa (70 km from the base station) , both analogue and CDMA calls could be established and easily maintained with good quality. During this time an unobstructed view of the Mt Dowe base station to the East was observed.
Upon entering Wee Waa, both CDMA and analogue call quality degraded, this was as a result of the buildings and other local obstructions in the town.
Limited handheld CDMA calls could be made in Wee Waa but only at selected locations and coverage was noted as patchy.
On leaving Wee Waa, CDMA speech quality immediately improved and the call held until 109 km from Mt Dowe.
Intermittent CDMA calls could be made at this location as could analogue, however quality was very marginal.
An analogue call was again established and the drive continued until the call dropped once at 122 km, and then again at 124 km. Over the distance 109 km to 124 km, analogue speech quality was very noisy and often completely unintelligible.
Reliable calls could not be established on either technology beyond 124 km.
Driving back towards Wee Waa, a CDMA call was established at 123 km with good call quality at this location, however quality was patchy, as was analogue along the road in this area.
As an extreme test of CDMA performance, a successful handheld call outside the vehicle was made at a distance of 118 km from the base station.
This test drive established that the CDMA and analogue coverage from Mt Dowe is very comparable with reasonably equivalent call quality and coverage noted.
At the edge of coverage between 109 and 123 km, the signal quality is generally unreliable for both technologies,
being affected by crests and dips in the road, trees & local obstructions.
Test Route 2 - Narrabri to Burren Junction via Wee Waa
The drive route for this test commenced at Narrabri, passed through Wee Waa, and then to Burren Junction some 118 km from Mt Dowe. Up to Burren Junction, CDMA quality was excellent with no apparent degradation, except when passing through Wee Waa as previously noted.
Entering Burren Junction, the CDMA call dropped once, but could be re-established intermittently in the town. Once again, local obstructions from buildings were the likely cause of the degradation. From Burren Junction onwards, CDMA showed patchy coverage until the drive concluded at 122 km.
Returning to the 112 km mark, an analogue call was established and the drive repeated through Burren Junction. As with CDMA, the analogue call held until entering Burren Junction. However a notable difference was that the analogue speech quality was noisier and noticeably poorer than CDMA in this area.
Unlike CDMA, no analogue calls could be established past Burren Junction.
Several stationary spot checks were performed at a location in Burren Junction. Whereas CDMA calls could be reliably established with good speech quality, analogue calls could only be established after repeated attempts, and showed marginal speech quality.
This test drive showed CDMA coverage as marginally better than analogue in terms of quality and absolute coverage. The coverage distance from Mt Dowe was similar to that achieved on the first drive route.
Conclusions
The two test drives conducted clearly showed that CDMA and analogue coverage in this area are very comparable, with CDMA marginally better on one drive route and very similar to analogue along the other.
In all tests CDMA maintained very high call quality.
The tests have demonstrated that using the Nortel Boomer Cell, Telstra CDMA can provide coverage over land at distances in excess of 100 km, subject to base station location, height and surrounding terrain.
It was noted that the distances achieved were consistent with the radio path horizon and intervening terrain in this area, beyond which earth curvature limits the radio signals.
All the Way with CDMA | More Details on Marine Coverage
<% call templateFooter %>