DAREN of WV News February 6, 2011(.969]
Kenneth Harris WA8LLM (304) 679-3470 email@example.com
WOOD COUNTY EMERGENCY COMMUNICATIONS
P.O. BOX 3328, PARKERSBURG, WV 26103
DAREN News, are articles and information about the Digital Amateur Radio "Emergency" Network of WV, which operates on 145.69 MHz. Anyone having any information about DAREN, or Amateur Radio in general, and would like to share it with others, may send it to WA8LLM @ PKBGWV on 145.69 MHz, or to my E-Mail: firstname.lastname@example.org. A State Wide DAREN NET is operated every Saturday from 7:00 pm to 10:00 pm, and lately, before and after those hours. The DAREN Net Announcement, showing the MAIN NCS, ALTERNATE NCS, NODEs accessible to both, and the previous week's check-ins, are posted by Thursday on most of the Main county DAREN PBBS'. The DAREN News can also be found on the wc8ec.org website.
A couple of weeks ago I said that Packet Radio is virtually error free because of the Error Checking and Error Correcting, and that it was a lesson in itself. How the Error Checking and Error Correcting is accomplished is simple. The transmitting station does a count of the data in each packet of information using a mathematical formula called Cyclic Redundancy Check or CRC. The answer of the CRC is inserted into the Check Count of the Packet Header. At the receiving end of the transmission the receiver uses the same formula to get the CRC. If the receiving CRC matches the transmitting CRC, then the data is assumed to be Error Free. If the Receiving CRC doesn't match the Transmitting CRC, then it is assumed there is an error in the data information. The receiving station will then tell the transmitting station the data is not error free, and asks for a re-transmission. Once the received CRC matches the re- transmitted data CRC, then the next Data Packet will be sent. Each Data Packet is verified the same way. It looks like the Data transmissions are therefore Error Free, but that is not always the case. If an error gets inserted into the data stream, it is possible the receiving station could come up with a CRC that matches the transmitting CRC, even though there is an error. The receiving station would assume the data is error free, and not question it. A lot of errors are inserted into the data transmissions if the path between the transmitter and receiver are noisy. In that case a lot of re-transmissions are necessary, and more errors may be inserted, and not be caught. Remember that only "connected" stations do Error Checking and Error Correcting. That means if the transmissions are Digipeated through several Digipeaters, the chances of errors are greater. Digipeaters DO NOT Error Check, they only repeat what they hear. If an error is inserted into the data stream between the transmitting station, and the first Digipeater, that error will be there when it gets to the Receiving station. The Receiving station must ask for a re-transmission. If an error gets inserted in the data stream when the receiving station is asking for a re-transmission, then the transmitting station will need to ask for a re- transmission. As you can see, there may be several transmissions and re- transmissions through every Digipeater in the path. When terminal stations use NODE Connecting, there are several "connected" stations in the path. Each Terminal station to NODE, and each NODE to NODE station, will do Error Checking and Error Correcting before the data is passed to the next location. In a long run NODE Connecting is better, and takes less time than Digipeating, even though it might take a little more time to set up a NODE path as opposed to Digipeating.
There were 63 check-ins to this week's State Wide DAREN Net. Francis Fox, K8ATB, who's been participating in the net since January 27, 2007, has completed 150 check-ins and will be receiving his certificate. John Peterson, K8ZPR, needs only one more check-in to make 850. Bob Tuckerman, W3RUA, needs only one more check-in to make 800. There were two new participates to the net this week and they were: Mike Maxson, W8SI, from Hurricane, and Paul Whited, KB8YZT, from Charleston. I want to welcome Mike and Paul to the DAREN system and hope they can participate in the net as often as possible.