Digital Net

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The NPARC Digital Net is currently held the 1st and 3rd Monday of each month at 9:00pm local time. The purpose of the net is to allow members to try out different digital modes and software with the hope that they become better acclimated to this facet of amateur radio. It was revived in June 2012 after a hiatus of about 2 years.

Contents

Net Protocol

The net will be run by the net control.

  • The net control will normally send out a message for a few minutes prior to net start along the lines of:
CQ CQ CQ NPARC Digital Net
CQ CQ CQ NPARC Digital Net de KC2WUF
The NPARC Digital Net will begin in the next few minutes
  • The net control will then ask for check-ins at 9:00pm with a message along the lines of:
CQ CQ CQ NPARC Digital Net de KC2WUF KC2WUF
CQ CQ CQ NPARC Digital Net de KC2WUF KC2WUF
Please send your call 2 or 3 times over the next 60 seconds de KC2WUF
  • Acknowledge each check-in and ask for more using something along the lines of:
K2XXX K2XXX QSL, QRZ NPARC Digital Net de KC2WUF k
  • Handle going through the list at least twice (if time permits), including asking for how everyone is copying each other.

Net Frequencies

Try and operate in or near the generally accepted operating frequencies for the mode being used for the net. As most club members checking in to the net are local, we can and sometimes do use bands that are closed for normal communications. Always publish the frequency of the actual signal so that net checkins can find the signal whether using USB (used for most modes and software) or LSB (considered the standard for RTTY, but not for all software). Some PSK center frequencies of late are: 7035.5 KHz and 28120.0 KHz.

Digital Modes

PSK31

PSK31 also known as BPSK31 is the most commonly used mode during our net. This mode allows for just about normal conversational typing speed, mixed case characters, as well as inline corrections during the conversation. When there is any interference (QRM or QRN) the text usually becomes garbled and uninteligible.

RTTY

RTTY is considered by many as the original digital (as long as you exlcude CW). This mode also allows for just about normal conversational typing speed. It is upper case only and has no provision for inline corrections during the typing. When there is low-level interference (QRM or QRN) causing single bit loss, you can usually interpret the text based on knowledge of the coding scheme. Dave Barr, K2YG, gave an excellent talk on RTTY in 2012 that explains why this is so.

Feld Hell

Feld Hell is a version of Hellschreiber that was one of the first "digital" modes used in radio. This mode works in a manaer analogous to ticker tape. We recently held a net (12/17/2012) in this mode in honor of our club expert on this mode. Although the group was small, the mode was enjoyed by all.

Digital Software

There are many programs for doing digital modes with a computer. Some are Operating System (OS) specific, while some are available on most OSes. Some of the programs are listed and include the modes and OSes. Please feel free to add or expand upon the entries as you see fit.

MMVARI

MMVARI was written by the same author as MMTTY, but handles PSK, RTTY and MFSK modes. It is nice since you can log all text transmitted and recieved to a file automatically with a single click. It also has a net feature which allows you to continue transmitting on a set frequency while following the received signal (Net Control Station) or transmitting on the same frequency as the received frequency (Net Participant Station).

FLDIGI

DM780

Digipan

Cocoa Modem

MMTTY

External Links

  • MMVARI
  • FLDIGI
  • DM780
  • Digipan
  • Cocoa Modem
  • MMTTY

NPARC also maintains a 'Digital Modes' web page. Discuss this web page in 'Discussion' (see upper left of page). It needs significant work on content and correctness.

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