[222mhz] ACSB

[cboone at earthlink.net]

ACSSB hasnt changed since the early days...the "pilot" tone is 10db down from max carrier out (It does do 0dbC at inital keyup then drops to -10dbC after 10-100ms iirc; by that time, the rcvr should have synced onto the pilot and thus the lower level can be used; much like the inband 3825 Hz pilot tone -used for E&M signaling- on SSB multiplex for analog FM microwave) and is 3.100 kHz from lowest end of the channel. The pilot is also low level FMed for PL/DPL use. 

As to getting them up on the 222-225 MHz range, it will be rough. The CPU mask is probably written to prevent out of range programming. You would have to come up with a new PLL control system or a new CPU with a new mask that allows programming outside the 220-222.0 range. Shame that it cant if SEA confirms that.

ACSSB did not ever take off on 220 (or even VHF HiBand for that matter) and NOW very narrow band FM (2.5 kHz deviation) is being used there....so much for spectrum efficiency (and to think poor UPS got screwed in the end....ahhhhhh) I have seen LOTS of SEA 220 systems at several tower sites turned off or if they are turned on, noone is using them....they just sit there, occasionally burping for "home" channel purpose and IDs..What a waste.....Funny how Motorola got into it when FM was authorized...they do sell a CDM mobile on 220-222 and sell rptrs made by Spectrum Engineering out of Australia (They dont even sell their own repeater...does that tell you something?). One of my company UHF repeaters grabbed on to the 1.5 in Heliax used by a 220 system. I have tried to find the 220 antenna they took down (20ft fiberglass)....but the other 220 ant w/feedline is still on the tower (HMMM Sounds like a ripe site for a 220 rptr)

The gear IS good for parts (The combiner/duplexers are a little rough to make work for single channel 1.6MHz split rptrs according to Sinclabs..it can be done but not worth the effort); The PA will be great for an all mode xvtr to 220 from another band; so would the front end but the LO and IF will be screwy....but as to making them actually work on 222-225, thats gonna be rough....but I would be interested if there IS a way..Midland also sold some "Linear Modulation" radios for 220 (May have been ACSSB or possibly some form of QPSK...not sure) and I think they can be programmed for simplex above 222....but I have never confirmed that rumor (Midland has usually been good about allow their gear to go into amateur bands...once you dig the info out of an engineer at their factory ;)

Having real SSB repeaters on 222-225 would really be nice.....think of the range coverage, etc.....would beat any FM system....but again, if the radios cannot be reprogrammed, we are just SOL..funny, the HAMS would make more use out of it then the commercial guys ever did!

Chris
WB5ITT
224.5 / 224.8 (and loss two control / link channels in 220 range to ACSSB)
-----Original Message-----
>From: "Dr. Gerald N. Johnson" <g369n849j at weather.net>
>Sent: Nov 6, 2007 10:44 PM
>To: 222mhz at mailman.qth.net
>Subject: Re: [222mhz] ACSB
>
>On Tue, 2007-11-06 at 21:40 -0500, Glenn Little WB4UIV wrote:
>> Is there anything that prevents hams from using ACSB?  There seems to be a 
>> lot of ACSB 222 MHz equipment showing up.
>> 
>> I was given a ESP1000 trunking system to get it out of the shed.
>> 
>> Has anyone converted one of these to 222-225 MHz? Sea says lots of luck!. 
>> The manual does not describe the method of setting the synthesizer on 
>> frequency.
>> 
>> 73
>> Glenn
>> WB4UIV
>> 
>The higbband ACSB board and manual I acquired decades ago wasn't all
>that wild for circuitry. Those days it was probably crystal controlled
>with the control tone about 3 KHz. That operated the squelch and the AFC
>and the only odd thing in the receiver was an audio low pass filter with
>a notch at the tone frequency. The major oddity in the transmitter was
>sending that tone with the voice audio.
>
>A trunking system may be difficult to get set on a ham frequency without
>it wanting to get a command from the trunking control. Might have to
>find the control port of the synthesizer and cut that away from the
>trunking internal control and set up a PIC chip to drive it, which is
>likely to be serial.
>
>Its likely that a 222 SSB ham station only needs to cover 222.050 to 222.125, 
>if that much so it might be that a VXO and multiplier might replace the
>synthesizer. Then if you drop the transmitted tone, its simply a dedicated 
>SSB rig compatible with the ham rigs already on the band.
>
>73, Jerry, K0CQ
>