![]() It isn't the loss that is a problem (about 0.2dB), its the lack of shielding. They probably could not have picked a worse cable for this application. It has been reported by others, and confirmed also on our unit, ICOM in their infinite wisdom indeed used RG-58A/U for the jumper cables between the RX and TX units to the back of the chassis. If you look on the main board, right near the front, you'll see some more test pads, "MIN" which appears to also be detector audio, and "RSSI" which is the receive signal strength indicator pin. Yep, you guessed it, that's good old FM Detector audio. Right near that chip is a test pad labelled "DET". Near the middle of that board is the CMX589A modem chip. If you remove the top cover of the RX radio, you will see the RX interface board. In the RP-4000V, this is relatively painless. So, all the standard tests can be done to check the RF performance of the radio by utilizing the discriminator audio prior to the modem chip. Right up to the modem chip, the RX radio is still an FM receiver. While there isn't currently any test equipment on the market that can encode and decode D-STAR, there are some work arounds. The actual selectivity of the receiver was not tested at this time.įurther tests on the other repeaters will be performed as the opportunity presents itself. As you can see, it takes a stronger level from the adjacent channel interference to cause the RSSI to rise, but it still affects the RSSI. The receiver was also swept with a CW at both +/-12.5kHz from the operating frequency. You will notice that the curve is basically linear right up to about -72dBm, at which point the detector circuit obviously saturates (4.5VDC). The resulting data was graphed to produce the following: The signal was swept from -128dBm to -60dBm in 4dBm steps (source was an IFR 1200S). With no input, the RSSI voltage was 1.078VDC. This signal is an analog voltage, that appears to be in the range of 1-4.5VDC (depending on signal level).Īn RP-4000V was tested by applying a CW signal to the antenna connector, and measuring the corresponding RSSI voltage as the level was changed. This RSSI signal comes pretty much directly from the receiver IC (MC3356 in the RP2D, or TA31136 in the RP2V). Now, something that is immediately interesting about this is that all of the repeater modules have an RSSI signal that they send to the controller. Pin 6 - RSSI (Receive Signal Strength Indicator) It seems that the pinout of the RJ45 on the rear of all the repeaters is the same. This is what the IC-RP2V looks like inside: On the other hand, the repeater modules that need to do duplex require separate transmit and receive units. Since the RP2D can only operate half-duplex, it only needs an integrated transceiver. Some investigation will be required to see if the radio responds to other commands on the USB port (as defined in the ID-1 interface specification). This appears to be nothing more than perhaps an ID-1 in a rackmount case, presumably with some slightly different firmware. The pinout of this connector appears to be: There is a 16 Mbit x 8 Boot ROM (flash) (IC12), 32 Mbit x 16 Flash ROM (IC11), and 4 Mbit x 32 of SRAM (IC2, 3, 6, 7) on board.Īlso of note is that J6 is an RS-232 interface directly connected to the CPU (IC5). Interesting to note is that the ASSIST ports (ID-RP2L 10GHz link) connect via a 10MB/s ATM connection using LVDS (low voltage differential serial). ![]() Below is the block diagram of how it works. This is a picture of the ID-RP2C (click for zoom): There are some interesting things to notice when you peek under the hood of the repeater equipment. Something as simple as a manufacturing change may render this information inaccurate. While we will try to be as accurate as possible in the information we provide, there are no guarantees that it will work with your equipment. ![]() Further, you will probably be voiding your ICOM warranty, so you're on your own. Of course, it should go without saying that if you undertake any of the modifications listed on this page, you do so at your own risk. While the repeater modules look nice, there are always things that can be done to make them work better. D-STAR Modifications Repeater Modifications
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