And my push button hard-wired land line phone still amazes people on the other end with its clarity, and I have to keep asking everyone to repeat themselves through the garble boxes they're using. That stuff you designed??
Tubelab_com,
I remember the Barts Head term.
Another digital modulation scheme, 8VSB is for US digital TV broadcasts.
I talked to various TV engineers.
One of them had 4 each 60kW IOT RF amplifier tubes.
The combiner put out 238kW to the bottom of the transmission line at the base of the tower.
The "missing" 2kW made the combiner into a space heater.
I also talked to a Hospital support technician.
The day a high power 8VSB TV tower went on the air, the Hospital's patient monitoring system was brought to its knees, they had to call the station and get them to shut down and give them time to get a different way to monitor patients.
Another Hospital technician had a problem with their distributed RF patient monitoring system. It had 4 channels authorized at about 600MHz. One of the channels was not used. So an inventory system with a portable transmitter was employed, broadcasting on the unused channel. The patient monitoring system receiver RF bandpass filter passed all 4 channel signals to the Mixer.
2 Watts from the inventory transmitter overloaded the patient monitor's Mixer.
Either get rid of the Inventory transmitter, or get a different patient monitor system.
The things Hospital management and lawyers never thought of . . .
I remember the Barts Head term.
Another digital modulation scheme, 8VSB is for US digital TV broadcasts.
I talked to various TV engineers.
One of them had 4 each 60kW IOT RF amplifier tubes.
The combiner put out 238kW to the bottom of the transmission line at the base of the tower.
The "missing" 2kW made the combiner into a space heater.
I also talked to a Hospital support technician.
The day a high power 8VSB TV tower went on the air, the Hospital's patient monitoring system was brought to its knees, they had to call the station and get them to shut down and give them time to get a different way to monitor patients.
Another Hospital technician had a problem with their distributed RF patient monitoring system. It had 4 channels authorized at about 600MHz. One of the channels was not used. So an inventory system with a portable transmitter was employed, broadcasting on the unused channel. The patient monitoring system receiver RF bandpass filter passed all 4 channel signals to the Mixer.
2 Watts from the inventory transmitter overloaded the patient monitor's Mixer.
Either get rid of the Inventory transmitter, or get a different patient monitor system.
The things Hospital management and lawyers never thought of . . .
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I moved around to different design engineering jobs inside Motorola. I would change every 3 to 5 years to learn new stuff. I did about 3 years in cell phone design, but that group was very cut throat with "climbers" doing anything they could to further their careers at the expense of the team.
What happens when you get 50 engineers in a big meeting meeting room and attempt to design a phone by committee? Nothing useful for sure, and if anything did come out of it, it would be a bland least common denominator kind of thing. The famous Razr was a "underground skunkworks" design done by 5 or 6 people without the knowledge of upper management. I worked best on these small teams and found my way onto several of them.
After I left the phone group in 2000, I got into an advanced research group. There I spent most of my time developing new technologies and designing and making Proof Of Concept devices to demonstrate the technology and show that it could be done. I stayed there until I was offered a buyout in 2014.
I had found out that Motorola's biggest competitor in the public safety radio market was working on a multi band handset. I brought this up to some high level marketing guys who told me that it was impossible, and they were not working on it.
About a year later the product development group authored a huge "white paper" showing in infinite technical detail exactly why it could not be done. My boss and I went over the paper to find their mistakes.....it sounded technically correct, but some assumptions were made. I said that it would be close size wise and thermal management would be the big issue. I asked the boss for permission to investigate further. I asked for another engineer, a parts guy, and 3 months.
There was a technical showcase meeting in Chicago in 5 months. After a little over three months I came back to the boss with two working POC radios. They could indeed talk to each other on all 4 different public safety radio bands used in the USA, albeit with a different software load for each band. This resulted in several patents and started the development of a quad band radio product, which is now shipping.
In another assignment I was told to devise a method to block the use of "TV white space" by low powered wireless devices, primarily those being pushed by a certain large software company for wireless game consoles. The idea was to use vacant TV channels in a given market for local "WiFi" like service on a listen then transmit basis. The TV and wireless microphone industry had already mounted a strong objection to this concept, since the demo devices tested were rather "dirty" transmitters that caused interference in weak signal areas.
My job was to show how unused TV channels could be used, and what it would take to do the job right. I developed a little 5 watt (peak) transmitter that could be fired up running 5 MHz wide LTE on an empty channel right in between two occupied TV channels in a weak signal market without interference. It worked well in testing, and was not technically difficult, but did not fit well with the expected $2 budget for the single chip design being proposed. Game over.
I remember being called out to an issue at the Orange Bowl stadium where the NFL Miami Dolphins played at the time (mid 1980's). Miami had just installed a state of the art multi zone trunked radio system to cover the entire county (2 million people). It seems that the zone near the stadium would go down as the stadium filled with people, then return to normal operation as they all left. Several teams had been out to the site on game day, and other days with all sorts of different test equipment, and all were unable to find the problem.
I was asked to investigate. I was a rookie engineer at the time, but I had been playing with electronics, ham radio and TV devices for years, so I tagged along, primarily to spend a day outside the plant. We pulled up at the Orange Bowl about an hour before game time with radios programmed up on the Miami Police system, and permission to use a maintenance talk group. There were several groups from Motorola present, along with a ton of test equipment, but almost everybody was concentrating on the 800 MHz frequencies used by the radios.
I stepped out of the van and wandered off, returning about a half hour later. I said that if the system goes down in 5 minutes, I know what the problem is. They looked at me like I was stupid, until the system went down 5 minutes later. Then I had everybody's attention. I dragged a few guys over to the NBC broadcast van that had a large dish on top to uplink the game to a satellite. That dish had 100+ watts of RF power at 12 or so GHz and it was aimed directly at the point to point microwave system linking the Orange Bowl zone to the rest of the system.
An agreement was made for NBC to move their uplink van a bit for the next, and future games to avoid blasting the link, and all was fixed.
Tubelab_com,
I did not do very much design work.
But I did consult some engineers on the design of a "flagship" spectrum analyzer model.
It had 10, 3, and 1MHz fixed resolution filters. I worked on the variable resolution filters from 300k to 3Hz.
Over a 2 year period, I went through 3 engineers on that module, with one just leaving that part of the project, with most of the time and successful work done by the second engineer, with the final engineer picking up the few easy loose ends, when the second engineer left for the country and farming to change his families lifestyle.
And I re-designed the 525MHz IF helical filters on that same analyzer. 50 thousandths of an inch at a time on the walls between the 5 resonators to check the coupling factors, using extremely loose coupled signal insertion and extremely loose signal pick off.
Checked the Q of an unloaded resonator, etc.
I had to re-design the tuning screws for better range, and adjust the taps on the input and output coils for the proper Q.
I used one of the engineer's programs, the chief engineer as a mentor, and Zverev's "Filter Bible" as I call it, to find the Q's, coupling values, etc. that I needed for proper bandwidth, shape factor, and group delay.
How I wish I could have had enough time to use different cuts in the walls between resonators. Using cuts that would alternate, top, bottom, top, bottom, top would have allowed me to not only get the group delay value I wanted, but would make it flatter across the top, instead of sloped versus frequency in the passband.
When you do a project, you find things that would make it so much better, but do not have time for.
During all that cutting, drilling, etc. the Model Shop showed me the proper and safe methods to do all that (they became very tired of me, I would measure, ask for more cutting, measure, ask for more cutting, etc.). Teach the person to fish, and get out of the fishing business.
Then I went to Marketing as a product support specialist. My former experiences in RF and microwave served me well.
Years earlier, I worked for a CW ultrasound doppler company. I redesigned the receiver RF amplifiers on their pocket models, at 2.5, 5, and 10MHz.
I also re-designed the oscillators on them, with less L, and more C, to prevent the frequency drifting as the semiconductors warmed up, and also made it easier to tune, since the next stage (output amplifier) no longer pulled the oscillator as the output stage's resonator was tuned.
It took me a long time to get to know my blood flow versus time, temperature, and lunch.
But then I was authorized to be QC on those models (QC with Body, Gell, Probe, and the Portable Ultrasound Doppler . . . think of all that as a system).
There was a Job in the orient for the state department, with complete antenna to typewriter communication systems, and typewriter to antenna systems. Re-pair, Installation, and whatever else came up.
A 2 year stint in a shipyard overhauling communication gear, radar, ECM, and even Sonar
was also good experience.
My first job in electronics was on a US Naval Destroyer in the middle of the pacific.
I fixed all sorts of communication gear, and finished a botched installation of a Low Freq. transmitter.
And stack gas and salt was murder on those antenna tuners.
I even helped the Radar Boys fix their radars a couple of times.
Before all that, I started my lifelong hobbyist and tinkerer "career".
I did not do very much design work.
But I did consult some engineers on the design of a "flagship" spectrum analyzer model.
It had 10, 3, and 1MHz fixed resolution filters. I worked on the variable resolution filters from 300k to 3Hz.
Over a 2 year period, I went through 3 engineers on that module, with one just leaving that part of the project, with most of the time and successful work done by the second engineer, with the final engineer picking up the few easy loose ends, when the second engineer left for the country and farming to change his families lifestyle.
And I re-designed the 525MHz IF helical filters on that same analyzer. 50 thousandths of an inch at a time on the walls between the 5 resonators to check the coupling factors, using extremely loose coupled signal insertion and extremely loose signal pick off.
Checked the Q of an unloaded resonator, etc.
I had to re-design the tuning screws for better range, and adjust the taps on the input and output coils for the proper Q.
I used one of the engineer's programs, the chief engineer as a mentor, and Zverev's "Filter Bible" as I call it, to find the Q's, coupling values, etc. that I needed for proper bandwidth, shape factor, and group delay.
How I wish I could have had enough time to use different cuts in the walls between resonators. Using cuts that would alternate, top, bottom, top, bottom, top would have allowed me to not only get the group delay value I wanted, but would make it flatter across the top, instead of sloped versus frequency in the passband.
When you do a project, you find things that would make it so much better, but do not have time for.
During all that cutting, drilling, etc. the Model Shop showed me the proper and safe methods to do all that (they became very tired of me, I would measure, ask for more cutting, measure, ask for more cutting, etc.). Teach the person to fish, and get out of the fishing business.
Then I went to Marketing as a product support specialist. My former experiences in RF and microwave served me well.
Years earlier, I worked for a CW ultrasound doppler company. I redesigned the receiver RF amplifiers on their pocket models, at 2.5, 5, and 10MHz.
I also re-designed the oscillators on them, with less L, and more C, to prevent the frequency drifting as the semiconductors warmed up, and also made it easier to tune, since the next stage (output amplifier) no longer pulled the oscillator as the output stage's resonator was tuned.
It took me a long time to get to know my blood flow versus time, temperature, and lunch.
But then I was authorized to be QC on those models (QC with Body, Gell, Probe, and the Portable Ultrasound Doppler . . . think of all that as a system).
There was a Job in the orient for the state department, with complete antenna to typewriter communication systems, and typewriter to antenna systems. Re-pair, Installation, and whatever else came up.
A 2 year stint in a shipyard overhauling communication gear, radar, ECM, and even Sonar
was also good experience.
My first job in electronics was on a US Naval Destroyer in the middle of the pacific.
I fixed all sorts of communication gear, and finished a botched installation of a Low Freq. transmitter.
And stack gas and salt was murder on those antenna tuners.
I even helped the Radar Boys fix their radars a couple of times.
Before all that, I started my lifelong hobbyist and tinkerer "career".
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