Can you mentally convert Lectrosonics or Zaxcom blocks to Megahertz without referring to a list? I certainly can’t.
There is a universal convention that we define radio frequency in Hertz. Exactly where does the block designation fit in?
If I told you my oldest son is two pickaxe handles in height, some of you might glean he is six feet tall.
Alternatively, if I said he was eighteen hands high, you might get the same impression if not cognizant that horses are measured to the top of their withers; not to their heads. According to that convention, my son is only five feet tall.
It makes little sense to use indirect, often meaningless, references.
While both pickaxe handles and hands are somewhat antiquated, both have some degree of historical relevance. The world is full of convenient de-facto standards. Your mother used cups and tablespoons as measures because these receptacles are commonplace in every kitchen. A 'pinch of salt' being another example.
If I told you my son was 135 blocks in height, you would be no wiser. What about a recipe where you are told to blend in three blocks of peppermint oil? Unless you know the height of a block, or teaspoon equivalent, the information is worthless.
When Sydney radio station 2SM first went to air in 1931, it was commonly listed as being on a wavelength of 236 metres. We used wavelength because frequency meters had yet to be invented and we could readily measure wavelength using Lecher Wires.
2SM was later referenced as 1270 kilocycles until NASA decided that cycles posed an ‘inconvenience’ for them as cycles had a entirely different meaning in their space lexicon.
Forty years ago, we immortalized Heinrich Hertz by standardizing on Hertz (Hz) instead of cycles.
There is a universal convention that we define radio frequency in Hertz. You get a lot of Hertz to the pound so we are inclined to use kilohertz (kHz), Megahertz (MHz) or Gigahertz (GHz) in the radio industry.
We often group segments of the radio spectrum into bands. For example, 2 metre band, 160 metre band, TV Bands I, III, IV and V. These do not imply a specific frequency, but rather a segment of the radio spectrum. For example, TV Band III is from 174 to 230MHz here in Australia. Bands can vary from country to country so adopting overseas conventions can be confusing.
A band is a ballpark indication, not a definitive frequency.
The advent of ‘Blocks’ was not derived from any logical convention. Didn't Lego invent them?
Back in the nineties, some U.S. manufacturers used to refer to their wireless mike frequencies by TV channel, e.g. 12-2 might be 204.750MHz within TV channel 12. Problem is that 12-2 is meaningless unless you have access to the manufacturer’s cross reference chart.
Even the information that it is on TV channel 12 can be misleading as TV channels vary from nation to nation. USA TV channels are six Megahertz wide, while many other nations employ seven Megahertz channelling.
When Lectrosonics developed their 200 series synthesized systems in the mid nineties, each system had 256 channels spaced 0.1 MHz apart. Total bandwidth was therefore 25.6MHz. While binary derived, 25.6MHz is an odd unit to handle.
If you go to the regulatory authority in the US, the FCC, and tell them you want to operate on Block 29, do you believe they will understand what you are asking? Think again.
Go to ACMA in Canberra and ask them if it’s OK to operate on Block 26 and they will view you as a Martian alien speaking some intergalactic gobbledygook.
Ask ACMA if it’s OK to operate your wireless mikes between 650 and 675MHz and they will immediately understand you. Even if you couch your enquiry as UHF Band V, they will understand what you are asking.
Both Megahertz and recognized bands are accepted industry parlance. Blocks are not. Contact NASA and ask them if the use of Block 21 might interfere with their communications and wait for the long and embarrassing silence.
Block numbers were originally devised as build designators as manufacturers cannot cover the entire UHF band with one build version. Here in Oz, it would take twelve Lectrosonics blocks to cover TV Bands IV/V).
The only way the block numbers have relevance if you can cross reference Block 22 as actually being 563.2 to 588.7MHz. If you can remember these limits, without referring to a written label or chart, why not say 563.2 to 588.7 instead of interposing the entirely meaningless Block number which has no relevance other than pointing towards a list?
How much simpler it would have been if they made versions over 25MHz bands, e.g. 600-625, 625-650, 650-675 and 675-700MHz. These could have been labeled Blocks 600, 625, 650 and 675; the number being the lower edge of each.
We would then have a situation where block 625 could easily be remembered as the band starting at 625MHz. How easy is that? Logical and meaningful.
The six ‘spare’ channels left over in each Lectrosonics version could overlap thus providing three common frequencies between each adjacent group. This compatibility might be useful in many scenarios.
Even if Lectrosonics were to make no changes, other than redesignating Block 22 to Block 563, that would at least convey that the block started at 563 MHz. That would cost little and go someway towards meaningful logicality.
Just as pickaxe handles and hand measurement units are legacies of the past, blocks have no legitimate parentage and are an unnecessary intermediary to Megahertz.
It has been said that a slight inclination of the cranium is the notional equivalent of a reflex action of a nictitating membrane to an equine quadruped devoid of its visual capacity.
I believe a nod is as good as a wink to a blind horse.
It's all in the way you express it.
© 2009 Microphone Magic