LARK AD6KV, 147.12 Repeater Coverage information
The following RF Plot maps were produced using the main repeater location and the remote receiver location. The green area indicates areas that usually have HT coverage, the blue area usually requires a mobile type radio and larger antenna, and the gray areas require even larger antennas. These maps are assuming that the user isn't hiding behind or inside of any buildings or other RF obstructing objects. The maps are approximate, so your actual results will be slightly different, but should be relatively close. Various labeled dots on the map are points of interest to the map creator. The numbered dots leading to the southeast are the mile markers on The Mines Rd.
The LARK Repeater Coverage Map shows the true coverage of the repeater. This is the area where the repeater can be heard and therefore is the true coverage of the repeater.
LARK Repeater Coverage Map
In addition, the LARK repeater has a remote receiver (operation described below). The areas shown in this map can be heard by the repeater, but users in these areas might not be able hear the repeater. A combination of BOTH maps is required to determine actual usable areas of the repeater (not available). The remote receiver is a receive-only site and acts as "listening-only" base station that receive the lower power signals of mobiles and portables, and relays the received signal to the actual repeater.
LARK Remote Receiver Coverage Map
If you look just at the repeater coverage map, the coverage isn't that great. When you look at the coverage of the remote receiver, it's easy to see that it is much better. (Please don't even ask why the repeater isn't at the hill site. It has to do with sharing the frequency with other repeaters.) Since both sites have receivers, but only the repeater site in Livermore has the transmitter, the actual coverage gets a bit odd.
The LARK repeater is located at VMC in Livermore. When it was placed there it was immediately noticed that many users in Pleasanton were having difficulties reaching the repeater, so a remote receiver and voting system was added to the repeater. Without a Voter is how most repeater systems operate. In this case, what is heard by the repeater antenna is what is transmitted by the repeater antenna.
The Voter system adds a second receiver, a Remote Receiver on Pleasanton Ridge and a Voter at VMC. When the Pleasanton Ridge receiver receives a signal, it is sent to VMC via an RF link. This Link signal is received at VMC then sent to the Voter. At the same time, most likely the same signal is being received at VMC by the main repeater receiver, and this signal is also being sent to the Voter. The Voter is obviously where the magic happens.
The Voter compares both signals, and sends the best one to the main repeater transmitter, and this best signal is what we hear from the repeater. It is also possible that the main receiver at VMC does not hear the originating signal, or the remote receiver does not hear the originating signal, and the Voter takes care of this, and the only received signal is transmitted.
If the area is in the Green on EITHER map, an HT is all that is normally required for the repeater to hear you. For you to hear the repeater with your HT, you should be in the Green area OF THE REPEATER COVERAGE PLOT.