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=====Regulation Lesson 4: Repeaters, Frequency bands =====

[[user:kurser:ham_vt2024|Back to course information]]

**Recommended reading for frequency bands: KonCEPT p. 282-283 (13.11 Bandplaner), 313-324 (Appendix F + G), 341-345 (Appendix N)**

**Recommended reading for repeaters: KonCEPT p. 168, 325 **

==== Frequency Bands ====

https://docs.google.com/spreadsheets/d/12-DGs_v8BtUYIoLHNqhQf3TM1EaVY1_BcL8CEh5m2vs

https://www.ssa.se/ssa/dokument/bandplaner/#elf_l1_Lw

https://www.ssa.se/vushf/bandplaner/

Ham radio frequency bands are bands you're allowed to transmit on if you have a license. Note: there are non-ham radio bands which everyone is allowed on (example: PMR446). Also, some ham radio bands are shared with other non-ham radio things (example: ISM @ 433.05 - 434.57 MHz and 2.4-2.5GHz, also WiFi/Bluetooth/microwaves). 

It is not allowed to use ham radio equipment on for example PMR bands! On ISM bands all equipment needs to be CE certified which ham radio equipment is not! 

**Legal**:

In sweden, frequency bands are defined in Post- och telestyrelsens föreskrifter om undantag från tillståndsplikt för användning av vissa radiosändare PTSFS 2020:5.

Coordination between countries is done by ITU. ITU's radio documents (radioreglemente) are guidelines and not legally binding for countries. They define not only ham radio, but divide the entire frequency spectrum for all kinds of services (television, industrial things, etc.). There are some differences between countries' band plans for ham radio.

**Bands**:

Explain overarching bands:
  * Low frequency (30kHz-300kHz)
  * Medium frequency (300kHz-3MHz)
  * High frequency (3MHz-30MHz)
  * Very high frequency (30MHz-300MHz)
  * Ultra high frequency (300MHz-3GHz)
  * Super high frequency ...
  * Extra high frequency ...
  * Terrific high frequency ...

Each band is referred to by it's approximate wavelength. Not exact (example: 40m band has a wavelength 41.6-42.8m). Mention λ[m] = 300/(f[MHz]) as rule of thumb!

You will need to know the start and stop frequency, as well as power of ALL the bands (probably nothing above 70cm comes on the test). Go through all bands (boring!)
  * Mention we have mounted antennas which work well on 40m, 20m, 17m, 15m, 6m (yagi), 2m (yagi), 70cm
  * Mention predominant modes used on the band. HF = SSB and AM, VHF is both SSB, AM and FM and UHF = FM.
  * Most bands are 200W PEP. Non-200W are italic
  * Propagation is best at HF. Probably ask -JKK about this!

Remember all modes have some bandwidth! Example if you're sending 3kHz USB @ 14.348, you're outside the band by 1kHz! Most radios know this, but some may only check the carrier frequency

Each band is divided by IARU into sub-bands, where it is recommended to use certain modes. In sweden, there's no legal requirement about what you send where, as long as you're in the band, under the maximum power and regularly send your callsign, you should be good. Other countries have different requirements.

Show page 2 in the spreadsheet.

You are not required to know these for the test, but other ham radio operators will be VERY angry if you break these (maybe tell story about guy who sent a bunch at 14.230 and complained about there being sstv there).


==== Repeaters ====

Problem: everything at VHF and above has very bad propagation. No ionosphere bouncing, doesn't penetrate rock and stuff well. You need to have line of sight. The optimal set up for a VHF station is high up with high power.

Some satellites have ham radio repeaters. Some satellites are ham-radio specific, while others (ISS!) happen to have a repeater on it. Need to control for doppler shift!

Repeaters are relay stations which listen at one frequency and transmits (relays) at another, with higher power and from a more strategic location. This means much better reception, especially with lower powered V-/UHF devices (handhelds).

Point of confusion: the TX frequency of the repeater is the RX frequency of your radio and vice versa. In the spreadsheet,

Repeater shift is the difference between the repeater's TX frequency and RX frequency. Each band has a standard repeater shift: on UHF the repeater TX frequency is 2MHz ABOVE the repeater RX frequency (negative repeater shift). On VHF, the shift is 600kHz.

Repeater channels: see slides. fd (före detta) = old format.

**Accessing repeaters**

Repeaters need some way to tell noise from signal. Some methods exist

  * Carrier wave detection (bärvåg): repeater activates when an FM carrier wave is detected over some threshold. (Not recommended by SSA, prone to being triggered by noise)
  * Tone burst (tonskur, tonöppning): Repeater is opened by a tone at 1750Hz (not baseband, but a tone inside the FM signal). After the frequency has been detected, the repeater stays open until the carrier is gone.
  * Subtone (CTCSS = continuous tone coded squelch system): Repeater is opened by a low tone (usually below 150Hz) in the FM signal. The tone used depends on the repeater. SSA has recommendation where different regions use different tones. Two nearby repeaters can use different tones to avoid having both repeaters open. Most UHF radios have settings to send this tone when transmitting.
  * DTMF (dual tone multi frequency): Some advanced repeater systems can be controlled and programmed by sending DTMF tones to it. These are the same kinds of tones pressing buttons on a dial phone produces. Not very common as the exclusive method of activation.

**Repeater nets**

(not on the exam, but good to know)

There are some systems which link together different repeaters over i.e. the internet. Example: SVXLink, brandmeister, echolink. Some people regard this as "cheating" and often disallowed in contests, but it is a very useful technology.

SVXLink is controlled by subtones, different subtones activate different "talk groups", controlling what repeaters around the country you activate.