Monthly Archives: April 2013

License free radio options

People frequently like to ask us what their license free radio options are for personal use.  Basically, there are three license free radio options other than Citizens’ Band radio:

One could easily argue that FRS is the most common license free radio option.  This is because FRS radios are sold in retail channels (such as Best Buy, etc.) and FRS has been around since 1996.  However, FRS radios are limited to an ERP of 500 milliwatts (half a watt).  FRS manufacturers generally claim exaggerated range. Because FRS is in the ultra high frequency (UHF) band, the presence of large buildings, trees, etc., will reduce range.  Under normal conditions, with line of sight blocked by a few buildings or trees, FRS has an actual range of about 0.5 to 1.5 km (0.3 to 1 mile).

MURS was established by the U.S. Federal Communications Commission in the fall of 2000.  MURS transmitter power output is limited to 2 watts.  This higher power output limit and the fact that MURS is in the very high frequency (VHF) band makes MURS have an increased range.  Also, MURS allows for external antennas, which FRS does not allow for.  Ranges of 10 miles or more are possible.

Both FRS and MURS do not allow for encryption.  On the other hand, radios on the ISM band frequently use Frequency Hopping Spread Spectrum, which enhances communications privacy.  This means that transmissions cannot be picked up on a radio scanner that someone might purchase from an electronics store.  Also, whereas FRS and MURS radios offer only one-to-many group communications, ISM band radios are capable of one-to-one as well as one-to-many.  These radios also offer enhanced capabilities due to their ability to transmit and receive data as well as voice; they can offer Caller ID and even Short Message Service (SMS) text messaging.

So, as you can see, there are many options for license free radio.  For the best “range”, you might choose MURS.  For the most privacy, you might choose Frequency Hopping Spread Spectrum radios on the ISM band.  If you have any questions about what radio might fit your personal license free radio needs, please don’t hesitate to contact us at (804) 625-4233 or sales AT richmondrf DOT com.

The digital standards and the manufacturers

In a previous blog post, we referenced the fact that digital standards are maturing.  So, while we were at IWCE, we started a spreadsheet to:

  • compare the digital standards
  • list which manufacturers are involved with which standards

Below is this spreadsheet.  You can learn a lot from it.  For example, there appear to be as many manufacturers focused on DMR (if you add in the Chinese manufacturers) as there are manufacturers focused on P25.  (This is pretty significant when you consider the marketshare of P25 in public safety agencies or the fact that EF Johnson and Midland only have P25 offerings.)

Enjoy!  And, if you see any typos/mistakes, please contact us at (804) 625-4233 or sales AT richmondrf DOT com.

NXDN

DMR

P25 Phase 1

TETRA

kHz

12.5 or 6.25

12.5

12.5

25

FDMA

TDMA

FDMA

TDMA

2-slot

4-slot

EF Johnson

Yes

Harris

Yes

Yes

Yes

Hytera

Yes

Yes

Icom

Yes

Yes

Kenwood

Yes

Yes

Midland

Yes

Motorola

Yes

Yes

Yes

Tait

Yes

Yes

Vertex Standard

Yes

 

The importance of good radio programming software

We have been spending a lot of time working with different radio programming software lately.  Some of the common flaws that we have seen:

  1. There is not a good way to move frequencies around in the programming software.  Cut, copy, and paste should be included in all radio programming software.  These functions have been around since the 1970s.  Why doesn’t all radio programming software have this?  For example moving a frequency from channel 14 to channel 7, should not require retyping the frequencies for channels 8 through 14.
  2. There is not a good way to share data between different models of radios.  For example, if you setup a handheld for the frequencies that you want to use, you should be able to reuse that programming to setup a mobile for the same system.  Again, this should not require retyping all of the frequencies for your channels.
  3. Because so much time is spent on developing great hardware, it appears that many radio manufacturers don’t spend enough time developing great programming software.  Much of of software that we have seen is just not very “user friendly.”

All of these issues above increase entry errors which, in a worst case scenario, can cause radios:

  1. to be on the wrong frequencies
  2. to be wideband when they should be narrowband
  3. to be unable to access the system because of incorrect CTCSS (PL) tones
  4. etc.

If radio manufacturers are unwilling to invest in radio programming software with simple features like this, maybe they should consider contributing to an open source radio programming software, like CHIRP.  (CHIRP is surely not perfect but it does solve the three problems mentioned above.)