Studio-technologies 45DC Uživatelský manuál stáhnout pdf (Strana 19)

Model 45DC User Guide Issue 1, January 2015

Studio Technologies, Inc. Page 19

If possible, prior to performing an auto null

it’s polite to warn all personnel who are ac-

tively using connected party-line intercom

devices. The tones sent to the party-line

circuit during the nulling process are not

excessively loud or obnoxious, but most

users might want to remove their headsets

during the process. In addition to warning

users, it’s a good idea to ask them to mute

any active microphones. Muting the mi-

crophones can be signiﬁcant as obtaining

a “deep” null requires that no extraneous

signals be present on the intercom circuit.

As previously discussed, if the Model 45DC

is supplying local intercom power the mi-

crophones will automatically be muted. But

for applications that connect to an existing

party-line intercom circuit the user’s must

manually mute the microphones.

The Model 45DC provides a call light sup-

port function, allowing call light signals

associated with user devices on two Model

45DC interfaces to work together. The

function also allows a Model 45DC inter-

connected with a Model 45DR Dante to

2-Channel Party-Line Intercom Interface to

have common call light activity. No opera-

tor action is required for the call light sup-

port function to perform its task. However,

placing DIP switch 1, located on the back

panel, to its on (up) position will disable the

function.

USB Interface

A USB type A connector and associated

status LED is located on the back panel of

the Model 45DC. This data interface is used

only for updating the unit’s application ﬁrm-

ware. No audio data of any kind will pass

through it. For details please refer to the

Technical Notes section of this guide.

Technical Notes

Call Light Support

A “call” or “call light” indication on a Clear-

Com party-line intercom circuit is transmit-

ted by way of a DC voltage that is applied

to the audio path, which is typically pin 3

of the interconnecting cable. This DC volt-

age is summed (added) to any audio that

is present. The Model 45DC detects when

a call light signal is active by monitoring the

audio path for the presence of a DC voltage.

A signal of approximately 5 Vdc or greater

is needed to indicate that the call function

is active. The Model 45DC can also gener-

ate a call signal by applying a DC voltage to

audio path. The DC, approximately 16 V, is

ramped up and down to minimize the addi-

tion of clicks or pops to the audio signal.

While the Model 45DC can detect and gen-

erate a call signal, it’s not possible to direct-

ly send and receive these DC signals over a

Dante interconnection that’s intended only

for audio transport. The Model 45DC works

around this issue by converting the DC call

light signaling to one that’s based on a 20

kHz audio tone. An astute user will recog-

nize this as the call method used by the TW-

series from RTS; instead of signaling via DC

in the audio path a 20 kHz signal is used.

In the “telco” world this would be referred

to as in-band signaling, not dissimilar to the

touch-tone dialing method that’s used on

analog telephone lines. But unlike touch-

tone signals, a 20 kHz signal has the advan-

tage of being above the hearing range of

most humans. This allows normal intercom

audio and a 20 kHz call signal to be active

simultaneously. And transporting this com-

bined talk/call signal over the Model 45DC’s

Dante connection shouldn’t be a problem

as a digital audio path that has a 48 kHz

1 2 ... 14 15 16 17 18 19 20 21 22 23

Komentáře k této Příručce

Žádné komentáře

Studio-technologies 45DC Uživatelský manuál Strana 19

Komentáře k této Příručce

Související produkty a manuály pro Zařízení Studio-technologies 45DC