The original Winchester small-scale DAB transmission site, as provisioned by UK DAB Networks, was the Arqiva mast at Crabwood Farm, Winchester. This mast is home to the BBC DAB antennae which was shared using an antenna combiner with the original Winchester small-scale DAB service.
Being a “premium site” with an antennae height of approximately 40m above ground level, it was calculated, (given the budget constraints required to ensure a sustainable business model for Winchester small-scale DAB), that it was economically unfeasible to continue in the use of this “premium site”. Thus we also had to accept that it may also be impossible to achieve quite the same level of signal coverage from an alternative, albeit cost-effective but lower height location.
Note: We appreciate from the outcome of the Ofcom consultation that there were opinions suggesting that a better site could be located. Given a) the time constraints that we were up against to bring services back on air as soon as possible in order to rescue a number of local businesses, b) our budgetary constraints, and c) the fact our chosen location is on the highest hill in Winchester and <200m from the original transmission site, we genuinely feel that this was a great location, and probably the best we could achieve given the pressures we faced.
Upon securing the new transmission site, at which an antenna height of approximately 15m was proposed, it was noted in our coverage predictions that there was an area within Winchester, north-west of St. Catherine’s Hill and Junction 10 of the M3 motorway, that required further investigation as it was uncertain if this would be cause for concern.
According to the original coverage predictions, this particular area near the centre of Winchester has always suffered from a small gap in coverage, but this was less prominent on the original Crabwood Farm coverage map compared to that of the new Flagstaff Stables prediction, naturally raising a potential cause for concern.
Upon further analysis, it was found that that the area in question could support a good level of outdoor signal reception, although indoor coverage may not be possible.
Our attempts to model improved coverage in this area were unsuccessful without either a significantly higher antenna or a significantly higher increase in transmitter power than requested in our proposal. It’s also worth noting that the original Winchester DAB service operated at 300W ERP and our new proposal requested 400W ERP to compensate for the significant height difference.
Since conducting a detailed analysis of the area, we have found that this coverage gap may not be such an issue after all, since the area is predominantly non-residential.
The coverage area in question encompasses the “Itchen Navigation Heritage Trail”, (formerly known as the “Itchen Navigation Footpath”), a nature area in a valley which follows two branches of the River Itchen alongside historic water meadows and the Iron Age hill fort of St. Catherine’s Hill nature reserve, as shown in the map below.
Our proposed technical plan aimed to ensure that the DAB coverage into the residential areas just outside the “Itchen Navigation Heritage Trail” area should meet indoor signal coverage requirements, without requiring the additional transmitter power required for indoor reception in the non-residential area, as shown in the map below:
It is our conclusion that the coverage gap may not be a genuine cause for concern. Please note, however, that predicted coverage maps do not guarantee coverage, so we will be looking to manually survey this area in the near future and ascertain actual signal performance, as opposed to theoretical, as detailed above.
Should our signal coverage into this area fall short of expectations, we would potentially seek to propose a future gap-filler once the operations and finances of the new Winchester DAB service have settled down.