Telecom Convertors for DS1/DS3 signals

Barton F. Bruce barton at
Tue Mar 28 09:47:36 UTC 2006

 > I am looking for recommendations for devices that can take a DS3 signal
> from a carrier via coax, convert it to optical so I can use fiber across
> buildings to transport the signal, type=A4PDF72&file=MRV-FD-SF

will do a T3 on a single fiber, but many similar products probably for less
$ will do it on 2 fibers.

> and then on the other side, demux the
> DS3 signal to individual DS1 channels and terminate them on a RJ-48
> port. Any suggestions? I am only looking at one DS3's worth of data to
> transport across buildings. Distance is around 1000 feet.

Any 1U M13 mux should be fine. Older several U high clunkers should be
avoided unless you already know and love some model. The 3 obvious brands
are Telco Systems, CAC, and Adtran.

Each has it features and problems, and vocal fans. I'll stay mostly neutral
in public but love/hate all 3 for different reasons.

Ebay $900 +/- $250 should get you one, but be sure you get TWO FULL main
cards on the Telco Systems or Adtran, or the 1:N spares in the CAC.
You definitely want as full a box as possible with all the built in
redundancy that brings.

You also want to inquire about software upgrades. They range from free
forever to OUCH each time depending on brand.

But normally "one DS3's worth of data" is NOT delivered on a channelized T3,
broken down to 28 T1s each of which could even be clocked at a
slightly different rate. ATM IMA? or MPPP? either ok with up to maybe 8 T1s?
Or what are you doing?

If it is true fractional DS3, the question would be what brand CSU/DSU was
or was being emulated at the far end - there is NO one standard, and an M13
MUX is totally WRONG. A cisco PA-2T3 used for $300 handles 2 T3s and with
about 3 different brands being emulated (ADC, Larscomm, DigitalLink), the
PA-2T3+ does more and costs more. The single port versions are often not
really much less used. A PA-MC-2T3+ (or the PA-MC-T3) can take the
channelised T3 and view it as 28 T1s or weird FT1 slicings, and works well
for MPPP up to maybe 8 T1s worth. But NOT ATM IMA. The PA-MC-2T3+ (but not
the single MC T3 one) also does full/fractional T3s the same way the PA-2T3+
does. PA-MC-T3 is channelised ONLY. Using the PA-MC... card as a cisco
router port card obviates the M13 in the channelised to T1/FT1 situation
unless you need an M13 to get T1s to feed the 8 port T1 IMA card.

Gruber ( makes a solid and cost effective 32 pair relatively
new (maybe 2-3 years) telco connector to RJ-48 panel, and can make the 32
pair cables (28 is also ok). This is NOT the very fancy and extremely
expensive one they once made for someone else that then sold them for some
insane price years ago.

Normal Male to Male cables will work with any brand, but only if using the
Telco Systems box, a "reverse entry" (pinned normally electrically but
90degree cable exit is on other side) is modestly better on the one cable
end for T1 OUT on the right side at the rear of the M13 (OUT == RECEIVE
DATA, fwiw). An alternate strategy is to order all 180 degree connector
hoods and then there are no cable exit direction issues but in all cases be
prepared to swap screwed on ty-wrapable clips for jack posts or longsize
(for cable connector to cable connector matings) self retaining 4-40 screws
for their shorter cousins needed for cable to bulkhead with jackpost
applications (see AMP's catalog). Peel and stick ty-down points are also
your friends as is waxed lacing twine.

180 degree hoods get ugly with 22ga ABAM. I assume your total T1 loop length
is quite short and the IN/OUT (Tx/Rx) signals will be similar levels. So
order 26GA non shielded cat-3 (or 24GA, but NOT 22GA). That is tiny,
flexible, and all you need. AMP's 24GA connectors are also used for 26GA -
not sure about the other brands, but whoever makes your cables should know.

You do have -48VDC handy, of course.

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