A 440 tone generator generator#
A 440 tone generator driver#
A 440 tone generator series#

A 440 tone generator series#

So, let’s see what happens when we generate the harmonic series using A=432 Hz as our foundation. However, this argument also highlights another problem: the notion that the reference pitch – the idea that the foundational frequency of our harmonic series should be an A.Īs we’ve discussed, ancient instruments, and even today’s modern brass instruments, use F and B-flat as their reference pitch. Whereas A = 432 Hz does show up as the Major 3rd harmonic of the Fifth (F) of our “magic frequency” of B-flat = 460.8 Hz (which we documented on the home page).

A 440 tone generator generator#

All I had to do was use Audacity’s tone generator on separate channels (for example, one channel with a 350 Hz tone and one channel with a 440Hz tone for the regular dial tone), and then combine everything down into a single mono channel.There’s a lot of discussion on the internet about A=432 Hz versus A=440 Hz – and, in my opinion, rightly so – because 440 Hz is an aberrant frequency with no grounding in nature. That’s right, it was completely computer-generated. The user can still either dial 911 or 9911 in an emergency, it’s just the outside dial tone will play after the first 9.īy the way, for that example wav file I showed above, I had considered recording the actual sound coming from the phones with a microphone, but I decided to do it all in Audacity instead. Note that all leading 9s need to have a comma after for this to work. That means that after every 9, enter a comma. If you happen to be in my same situation (or if you just want to use an outside dial tone that sounds better than that stupid single 440 Hz outside dial tone that the SPA504G defaults to), go to Admin, Advanced, Regional, Call Progress Tones, Outside Dial Tone, and use this: that to actually get the phone to play an outside dial tone, you must configure your dial plan to support it. The low tone is 90 Hz higher than the 350 Hz low tone of the dial tone, and the high tone is 90 Hz higher than the low tone. With that, I was able to narrow down the possibilities, and came up with 440 + 530 Hz for Cisco’s outside dial tone. A dial tone is 350 + 440 Hz (90 Hz difference), a ringing tone is 440 + 480 Hz (40 Hz difference), and a busy signal is 480 + 620 Hz (90 + 50 Hz difference). This apparently makes it easier to determine what two tones are being sent in a DTMF sequence. Through some reading, I eventually figured out that “special tone frequencies” are always in multiples of 40, 50 and 90 Hz.

Random fiddling came close, but it still sounded off. I could have probably figured it out if I had an oscilloscope, but I didn’t have access to one. I didn’t find anything online, and while many of the tones on the 7900s are sent to the phone by the call manager, the outside dial tone is hard-coded in the phone’s firmware. It’s customizable, so I started looking for what DTMF combination the 7900’s outside dial tone is. The SPA504G can be programmed to generate an outside dial tone, but it defaulted to a single 440 Hz tone, which just did not sound right. I always found the order to be backwards I figured the “inside” dial tone should be non-standard, and once you hit 9, you’d be presented with a standard North American dial tone. Here is a sample audio file of that process. When you press 9, however, that changes to a different dial tone, to signal that you are “outside” and can dial as if you were at a regular POTS phone. When you pick up the phone, you hear a standard North American dial tone (350 + 440 Hz). One of the features of the 7900 phones is a separate tone when reaching an outside line. In the last few weeks/months, I’ve been preparing to make this process as smooth as possible from a user perspective, since this is the most visible aspect to the employees. So now we’re replacing them with Cisco SPA504G phones, which use the industry standard SIP protocol. Everything mostly worked, but we lost the ability to do 3-way conferencing via the phones.

A 440 tone generator driver#

Unfortunately, the SCCP driver is graciously described as “beta” (remember, it’s a proprietary protocol). We had been preparing for this possibility, and had an Asterisk system ready that was able to talk SCCP to the 7900 phones. Earlier this year, the call managers died. The 7900s used SCCP, a proprietary but decently understood protocol to talk with the call managers. In the Reno and Salt Lake City offices, we had a Cisco Unified Communications VoIP system going back to 2001, with Cisco 7900 series phones. I’m currently in the process of upgrading our phone systems at work.