Interference causing stutter and bad controls - My theory and a potential solution
Posted: 06 Jun 2021, 04:33
Okay, so I've been experiencing the same things many users on this forum have: erratic aim, slow response and input delay caused by some form of external interference.
I'm not a PC gamer, I currently am gaming on a PS4 Pro. I've had a crazy slow and imprecise lag on my controls for the last 1.5 years now. It changes depending on the day or time of day. It also changes depending on devices I use in my apartment.
My theory may be just another or correct/incorrect. I have a background in audio hardware and I've done a lot of experimentation and research into this issue in my home. I've noticed a lot in my experiments, but one thing that stands out to me: my iPhone charger.
I've noticed my controls feels different when using random appliances in my apartment. Though it's not always consistent. X device powered on, I may feel like I have slower controls one day, yet on the next day with X device powered on it doesn't feel as slow. Which leads me to believe most of my devices in my apartment aren't really contributing to the interference issues.
However, this isn't the case with my iPhone charger; the standard Apple 5V USB to lightning cable and USB plug. Every time I charge my iPhone in close proximity to my gaming setup, my controls without fail feel much slower and less precise. See, I don't use controllers in wireless mode. In fact, my current controller is the Thrustmaster eSwap PRO and my last controller was an original Razer Raiju - both of which do not use a wireless transmitter, they are strictly USB powered. So the interference is being picked by the USB cable and/or controllers internal electronics.
Going back to the iPhone charger, you might think "Well aren't smartphones going to cause interference anyway? Shouldn't you place your phone at least say 5+ metres away from your controller?". Yes and no. USB devices generally use a carrier frequency of 2.5GHz, this is the frequency devices send/receive at. If your smartphone drops down to 2G mode on your mobile network and/or you're using 2.4GHz Wi-Fi, this will cause interference to your USB device.
So is this the answer? No. My iPhone is always in Airplane Mode and I disabled the 2.4GHz transmitter on my router, I strictly use 5G for Wi-Fi. There should theoretically be no issues, having my iPhone charge 1 metre away shouldn't cause any interference. I have read that some smartphones even when Airplane Mode is enabled, can receive and transmit mobile signals, but the signals are much lower in power, this won't be a problem. However, again, why is it when my iPhone charges that I experience slow and imprecise controls? Well, it must be the charger itself.
Almost every electronic device you own will use something called a switch mode power supply. This is a type of power supply that converts AC to DC, using a fast switching process. There are many different designs and architectures, generally a switch mode power supply will switch from the KHz to the MHz range. Cheaper switch mode power supplies will generally switch in the KHz range, the more expensive audio focused in the MHz range. Some don't use a static frequency, they can change depending on the power load.
What has that got to do with USB? Doesn't USB use a 2.5GHz carrier frequency? Yes it does, to send/receive data between USB devices. However, as I recently had found out, there's much more to it. See, I'm somewhat familiar with electronic clocks. Expensive digital audio products are often touted as using high performance master clocks and high-end record studios often use external master clocks. What do they do? They control the timing of digital signals. The best master clocks have extremely low jitter, a bad clock with have high jitter. Jitter is the measurement of timing performance. In a low jitter system, connected devices will be close to being in perfect sync with each other - data will be sent/received/used exactly when it needs to without a hiccup. In a system with jitter issues, devices will be very far from operating in perfect sync - bad timing will cause data to be sent/received/used too early and/or too late than needed.
The USB standard does not use any of the pins to connect each devices clock together. Unlike other types of digital interfaces, there is no dedicated clock signal. This is why even the inventor of USB says it's not the best interface for audio, as the lack of a clock lane limits its timing performance for sensitive signals such as audio. Every modern digital interface still needs to sync signals however, so USB does use a clock. I'm not the most knowledgable person on the USB interface, but from research a device such as a PC or game console will usually house 2 clocks used for USB devices. One main clock connected to the system and a second clock for USB signals that is connected to the system clock. System clocks generally oscillate from 30KHz to 16MHz, USB clocks generally oscillate at 48MHz.
Look at the frequency ranges above. From KHz to MHz. Exactly the frequency range switch mode power supplies operate in. There is research already in this area and EMI can in fact affect the performance of crystal oscillators and therefore increase system jitter. The Apple USB to Lightning cable is not shielded and there are no ferrite chokes on the cable. This means the cable is radiating EMI like an antenna.
Aren't products designed to suppress EMI!? Isn't this pursuit getting into the snake oil salesman area??
Products have to conform to EMC regulations. I will simplify this a bit though, there are generally 2 classes. A consumer and a pro class. In the pro class products, which are generally very expensive industrial/scientific equipment that must be designed to be as immune to interference as possible are tested to very high standards - to make sure they block out almost all external interference and also radiate very little. The consumer class is tested thoroughly, but to a much lower degree and with a lot more tolerance on how much interference devices can both block out and radiate. The vast majority of electronics companies design products to pass the bare minimum, to just about pass testing and nothing more. Any situation or environment that has interference above their testing threshold will cause changes to the performance of your electronic device.
Consumer class EMC testing cannot account for every situation or environment. It cannot account for every nearby device or all other connected devices. It's a good generalised test to make sure consumer electronic devices have at least some decent level of EMI suppression and don't radiate too much, but it's not as strict as the pro class product testing and it isn't perfect. Products are generally tested to make sure they work under a certain load, but not necessarily perform at optimum performance.
My explanation on EMC testing was probably boring to read, but it was to shed light on the fact that yes, electronic devices are built so that interference shouldn't be a problem - but it often still is. Switch mode power supplies radiating EMI is actually a very common problem. You can search on YouTube yourself for radio enthusiasts picking up high amounts of noise on certain radio bands, which they identify to be caused by a switch mode power supply in their room - as a solution, they suppress this noise by wrapping the power supply cable in a ferrite ring or choke. A ferrite choke will not be the solution in every situation however. Depending on the source of the interference, one may have to take a holistic view on the entire system or room. The source could of your KHz - MHz interference could be your: PC PSU switching at the same frequency as your MOBO USB clock, your router/modem power supply, your LED lights, your monitor, your audio products, a local radio station, etc. There could be a number of sources.
For me, even when I'm not charging my iPhone, my controls are still not flawless. As I don't know exactly all the sources contributing to my interference issues, I'm going to use a more brute force method of EMI suppression. I recently bought a Furman Elite mains conditioner which suppresses EMI in the KHz to GHz range. The ranges below the Elite range do not filter KHz range EMI - I have seen some users here buying the budget Furman mains conditioners, this may be why they don't do anything. I'm just waiting on power cables for it, so I don't know how much of a difference it will make. I'm also going to buy ferrite rings and chokes for all my cables (power and data) and switch mode power supplies to stop the antenna affect of the cables - at least one choke on each end. I'm already using a cheap shielded USB cable, but I'm going to buy a passive USB filter called the Wurth Elektronik 829993STICK designed to suppress EMI in the KHz to GHz range on both the USB data lane and power lane.
If your electronic devices are to blame for your interference issues, that could explain how some people have moved to different locations and still experience it and people trying their system at a friends house surrounded by different electronic devices. If the main source is from radio stations, that would explain people moving home and the problem going away. As my theory suggests, I believe the issue we are all experiencing is external interference reducing the timing performance of our devices USB and system clocks. Taking a holistic approach to suppressing EMI from interfering with these digital clocks may be the answer.
Since just making my account, I should be ok these forums quite frequent. So I can keep people who wants to know updated, hopefully my set of solutions works for me. If there's anyone in here more knowledgable than me on USB that found any inaccuracies in my post, please let me me know so I can understand the interface better.
I'm not a PC gamer, I currently am gaming on a PS4 Pro. I've had a crazy slow and imprecise lag on my controls for the last 1.5 years now. It changes depending on the day or time of day. It also changes depending on devices I use in my apartment.
My theory may be just another or correct/incorrect. I have a background in audio hardware and I've done a lot of experimentation and research into this issue in my home. I've noticed a lot in my experiments, but one thing that stands out to me: my iPhone charger.
I've noticed my controls feels different when using random appliances in my apartment. Though it's not always consistent. X device powered on, I may feel like I have slower controls one day, yet on the next day with X device powered on it doesn't feel as slow. Which leads me to believe most of my devices in my apartment aren't really contributing to the interference issues.
However, this isn't the case with my iPhone charger; the standard Apple 5V USB to lightning cable and USB plug. Every time I charge my iPhone in close proximity to my gaming setup, my controls without fail feel much slower and less precise. See, I don't use controllers in wireless mode. In fact, my current controller is the Thrustmaster eSwap PRO and my last controller was an original Razer Raiju - both of which do not use a wireless transmitter, they are strictly USB powered. So the interference is being picked by the USB cable and/or controllers internal electronics.
Going back to the iPhone charger, you might think "Well aren't smartphones going to cause interference anyway? Shouldn't you place your phone at least say 5+ metres away from your controller?". Yes and no. USB devices generally use a carrier frequency of 2.5GHz, this is the frequency devices send/receive at. If your smartphone drops down to 2G mode on your mobile network and/or you're using 2.4GHz Wi-Fi, this will cause interference to your USB device.
So is this the answer? No. My iPhone is always in Airplane Mode and I disabled the 2.4GHz transmitter on my router, I strictly use 5G for Wi-Fi. There should theoretically be no issues, having my iPhone charge 1 metre away shouldn't cause any interference. I have read that some smartphones even when Airplane Mode is enabled, can receive and transmit mobile signals, but the signals are much lower in power, this won't be a problem. However, again, why is it when my iPhone charges that I experience slow and imprecise controls? Well, it must be the charger itself.
Almost every electronic device you own will use something called a switch mode power supply. This is a type of power supply that converts AC to DC, using a fast switching process. There are many different designs and architectures, generally a switch mode power supply will switch from the KHz to the MHz range. Cheaper switch mode power supplies will generally switch in the KHz range, the more expensive audio focused in the MHz range. Some don't use a static frequency, they can change depending on the power load.
What has that got to do with USB? Doesn't USB use a 2.5GHz carrier frequency? Yes it does, to send/receive data between USB devices. However, as I recently had found out, there's much more to it. See, I'm somewhat familiar with electronic clocks. Expensive digital audio products are often touted as using high performance master clocks and high-end record studios often use external master clocks. What do they do? They control the timing of digital signals. The best master clocks have extremely low jitter, a bad clock with have high jitter. Jitter is the measurement of timing performance. In a low jitter system, connected devices will be close to being in perfect sync with each other - data will be sent/received/used exactly when it needs to without a hiccup. In a system with jitter issues, devices will be very far from operating in perfect sync - bad timing will cause data to be sent/received/used too early and/or too late than needed.
The USB standard does not use any of the pins to connect each devices clock together. Unlike other types of digital interfaces, there is no dedicated clock signal. This is why even the inventor of USB says it's not the best interface for audio, as the lack of a clock lane limits its timing performance for sensitive signals such as audio. Every modern digital interface still needs to sync signals however, so USB does use a clock. I'm not the most knowledgable person on the USB interface, but from research a device such as a PC or game console will usually house 2 clocks used for USB devices. One main clock connected to the system and a second clock for USB signals that is connected to the system clock. System clocks generally oscillate from 30KHz to 16MHz, USB clocks generally oscillate at 48MHz.
Look at the frequency ranges above. From KHz to MHz. Exactly the frequency range switch mode power supplies operate in. There is research already in this area and EMI can in fact affect the performance of crystal oscillators and therefore increase system jitter. The Apple USB to Lightning cable is not shielded and there are no ferrite chokes on the cable. This means the cable is radiating EMI like an antenna.
Aren't products designed to suppress EMI!? Isn't this pursuit getting into the snake oil salesman area??
Products have to conform to EMC regulations. I will simplify this a bit though, there are generally 2 classes. A consumer and a pro class. In the pro class products, which are generally very expensive industrial/scientific equipment that must be designed to be as immune to interference as possible are tested to very high standards - to make sure they block out almost all external interference and also radiate very little. The consumer class is tested thoroughly, but to a much lower degree and with a lot more tolerance on how much interference devices can both block out and radiate. The vast majority of electronics companies design products to pass the bare minimum, to just about pass testing and nothing more. Any situation or environment that has interference above their testing threshold will cause changes to the performance of your electronic device.
Consumer class EMC testing cannot account for every situation or environment. It cannot account for every nearby device or all other connected devices. It's a good generalised test to make sure consumer electronic devices have at least some decent level of EMI suppression and don't radiate too much, but it's not as strict as the pro class product testing and it isn't perfect. Products are generally tested to make sure they work under a certain load, but not necessarily perform at optimum performance.
My explanation on EMC testing was probably boring to read, but it was to shed light on the fact that yes, electronic devices are built so that interference shouldn't be a problem - but it often still is. Switch mode power supplies radiating EMI is actually a very common problem. You can search on YouTube yourself for radio enthusiasts picking up high amounts of noise on certain radio bands, which they identify to be caused by a switch mode power supply in their room - as a solution, they suppress this noise by wrapping the power supply cable in a ferrite ring or choke. A ferrite choke will not be the solution in every situation however. Depending on the source of the interference, one may have to take a holistic view on the entire system or room. The source could of your KHz - MHz interference could be your: PC PSU switching at the same frequency as your MOBO USB clock, your router/modem power supply, your LED lights, your monitor, your audio products, a local radio station, etc. There could be a number of sources.
For me, even when I'm not charging my iPhone, my controls are still not flawless. As I don't know exactly all the sources contributing to my interference issues, I'm going to use a more brute force method of EMI suppression. I recently bought a Furman Elite mains conditioner which suppresses EMI in the KHz to GHz range. The ranges below the Elite range do not filter KHz range EMI - I have seen some users here buying the budget Furman mains conditioners, this may be why they don't do anything. I'm just waiting on power cables for it, so I don't know how much of a difference it will make. I'm also going to buy ferrite rings and chokes for all my cables (power and data) and switch mode power supplies to stop the antenna affect of the cables - at least one choke on each end. I'm already using a cheap shielded USB cable, but I'm going to buy a passive USB filter called the Wurth Elektronik 829993STICK designed to suppress EMI in the KHz to GHz range on both the USB data lane and power lane.
If your electronic devices are to blame for your interference issues, that could explain how some people have moved to different locations and still experience it and people trying their system at a friends house surrounded by different electronic devices. If the main source is from radio stations, that would explain people moving home and the problem going away. As my theory suggests, I believe the issue we are all experiencing is external interference reducing the timing performance of our devices USB and system clocks. Taking a holistic approach to suppressing EMI from interfering with these digital clocks may be the answer.
Since just making my account, I should be ok these forums quite frequent. So I can keep people who wants to know updated, hopefully my set of solutions works for me. If there's anyone in here more knowledgable than me on USB that found any inaccuracies in my post, please let me me know so I can understand the interface better.
