From e5b572968ceb6d1734357d1fb6eb6fe64e8d752c Mon Sep 17 00:00:00 2001 From: thomasabishop Date: Sat, 21 Feb 2026 12:13:58 +0000 Subject: [PATCH] additional ham notes --- zk/Calling_CQ.md | 19 +++++++++++++++++++ zk/Digital_voice_and_data_modes.md | 25 +++++++++++++++++++++++++ zk/Repeaters.md | 25 +++++++++++++++++++++++++ zk/Signal_reports.md | 17 +++++++++++++++++ 4 files changed, 86 insertions(+) create mode 100644 zk/Calling_CQ.md create mode 100644 zk/Digital_voice_and_data_modes.md create mode 100644 zk/Repeaters.md create mode 100644 zk/Signal_reports.md diff --git a/zk/Calling_CQ.md b/zk/Calling_CQ.md new file mode 100644 index 0000000..6118655 --- /dev/null +++ b/zk/Calling_CQ.md @@ -0,0 +1,19 @@ +--- +tags: [radio, ham-study] +--- + +The term "calling CQ" means making contact with other amateur radio operators. +There is an established protocol for doing this. Below is the convention for 2m +communications (VHF): + +1. Tune to the _calling frequency_ for the band. For VHF this is 145.500 MHz. +2. Check that the calling frequency is not currently in use. +3. If free, call for a specific call sign, or, for general contact call "CQ". +4. Once you have found someone, find _another_ free frequency (not the CQ + frequency) and ask/check that it is not in use. +5. If it is free, return to the calling frequency and direct your contact to the + new frequency. + +> Each of the main frequencies on the band plan will specify a "center of +> activity". This is where to start listening of contacts for the frequency when +> establishing CQ. diff --git a/zk/Digital_voice_and_data_modes.md b/zk/Digital_voice_and_data_modes.md new file mode 100644 index 0000000..7dbb6dd --- /dev/null +++ b/zk/Digital_voice_and_data_modes.md @@ -0,0 +1,25 @@ +--- +tags: [radio, ham-study] +--- + +Digital voice (DV) radios are the same as normal analog radio but the vocal +sound wave is sampled and converted into digital information (bits) and +transmitted in this format. + +This provides better audio quality for weak signals and transmits more +efficiently than analog (i.e. using less bandwidth). + +There are various DV systems and generally they are not compatible with each +other. (Examples include D-Star and C4FM). + +DV can only be used on certain frequencies so it is important to check the band +plan. + +> DV radios often embed the call sign within the transmission. If using someone +> else's equipment, or second-hand equipment, you need to make sure to reprogram +> the call sign. + +"Data modes" means transmitting anything other than voice or CW via SSB, FM, AM. +This is transmitted digitally like DV. + +21 diff --git a/zk/Repeaters.md b/zk/Repeaters.md new file mode 100644 index 0000000..0f34c52 --- /dev/null +++ b/zk/Repeaters.md @@ -0,0 +1,25 @@ +--- +tags: [radio, ham-study] +--- + +Repeaters exist in order to extend the range of mobile stations. They are +designed to solve the line-of-sight problem associated with VHF/UHF, receiving +your signal and re-transmitting it at much higher power, extending the range of +low-powered portable devices. + +Repeaters **have an input and output frequency** so that they can receive and +transmit at the same time. On VHF, repeaters typically transmit at 600KHz above +their input (receiver) frequency. The difference between the transmitting and +receiving frequency is known as the "offset". + +In order that the repeater can distinguish intentional communication from noise, +it will use CTCSS tones. These are non-audible low-frequency tones that are +transmitted along with your audio. The repeater will only activate if it "hears" +the right tone. You have to program your radio to transmit the right CTCSS tone +for the specific repeater. In the UK there are 9 blocks of tones. + +> It is important that you do not use the calling frequency of a repeater for +> normal two-way communication (simplex). This would prevent people from using +> the repeater. When you are agreeing on a shared frequency for CQ, ensure you +> are not accidentally using a repeater frequency. The repeater frequency (and +> its offsets) should only be used for repeater-relayed communication. diff --git a/zk/Signal_reports.md b/zk/Signal_reports.md new file mode 100644 index 0000000..e7ac3a2 --- /dev/null +++ b/zk/Signal_reports.md @@ -0,0 +1,17 @@ +--- +tags: [radio, ham-study] +--- + +Signal reports are used for reporting on the quality of a given frequency. + +There are three values comprising **RST** (Readability, Signal, and Tone). Tone +is only used for [CW](./Frequency_modulation.md). Each value is given its own +score: + +| Signal value | Scores | Meaning | +| ------------ | ------ | ----------------------------------------------------------- | +| Readability | 1,3,5 | Unreadable, readable with some difficulty, totally readable | +| Signal | 1,5,9 | Faint, fairly strong, very strong | +| Tone | 1,5,9 | Rough, some ripple. pure | + +A very good signal report is therefore known as a "five and nine".