WWVB Loopstick Antenna & C-Max Receiver

© Brooke Clarke, 2003 - 2022

7.5" rod

2.5" rod

Background

Bank Winding

The following explanation of "Bank Winding" is for a 4 layer coil.
"Bank Wound" means that you start the winding at the left end, then make 4 turns then wind backwards for 3 turns then forward for 2 turns and then backward for one turn.  Now there are 4 layers of wire all at the left end.  This process is repeated until the length of the rod is covered.  The important fact about this type of winding is that the electrical distance from any one turn to it's immediate neighboring turn is is just a few turns.  If the coil was wound a layer at a time, then the electrical distance between turns may be hundreds of turns.  The self capacity of the completed coil depends on both the capacity between adjacent turns and also the voltage between the turns.

If you look at the equivalent circuit for a single layer coil where the turns are spaced about one wire diameter it can easily be seen the the total coil voltage is divided so that 1/N of the voltage is across each turn-to-turn capacitance.  That's to say the capactance is very closd to the capactance of the first to the last turn.  But if you added a second layer then the two coil terminals are at the same end and the turn-to-turn capacitance for the turns adjacent to the two terminals has 100% of the coil voltage across it.  The next turns away from the terminals has (N-1)/N of the full coil voltage, etc.  This results in a huge self capacity.

Litz Wire

There are a number of effects that cause the A.C. resistance of a wire to be higher than the D.C. resistance. 

Skin Effect

In a straight wire, with no other wires near by, as the frequency increases the electrons carrying the current move away from each other and so end up more and more near the surface of the wire and less and less along the centerline.

Proximity Effect

Is similar to Skin Effect, but is caused by the interaction between wires that are near to each other.

Litzenhardt wire is made up of a number of independent conductors that are insulated from each other.  There are a large number ways that the strands can be arranged.

The correct term may be Litzendraht, meaning Litzen (braided) Draht (wire) Thanks to John Portune W6NBC

The wire I used is made from AWG number 44 wires that are in bundles of 36 wires and there are 5 of these bundles in the final wire.  If you needed a cable with 180 seperate wires you could use this Litz wire that way.  Since a single # 44 wire has a diameter of 0.00198" the total area of the 180 wires is equivalent to a solid wire of diameter 0.02656", or between AWG 21 and 22.

The problem is the insulation takes up space that could be used for copper.  The result is that Litz wire typically only works well below a few MHz.  It's interesting that at mains power frequencies (20, 50 or 60 Hz) the largest size single strand wire you can buy is determined by skin effect.  If a load requires more square mills of copper area then you need to use multiple insulated conductors.

MWS - Litz tool - input the AWG size to get the cross sectional area and it tells you the available strand count and wire sizes.

Measured Data

The following plots were made using the HP (Agilent) 4395A in the Network Analyzer mode and using the Z Transform technique where the unknown device is placed in series with the center conductor.
The problem with this winding is that it's very difficult to bring it to reasonance because of the difficulty in finding fixed caps of the exact value you need.
A much better approach is to make the coil on a sliding former so tuning can be done simply by sliding the former.  That's the way the commercial WWVB antennas are made.

Imaginary Part of Impedance Plot	The marker shows 1.004 k Ohms at 32.960891 kHz. The network analyzer has already separated the real and imaginary parts so this is pure inductance. L = X / (2 * PI * F) = 4.83 mH
Real Part of Impedance Plot	You can see that at 100 Hz the real part of the impedance is about 1 Ohm.  i.e. the DC copper resistance. The marker shows the resistance has climbed to 29.325 Ohms at 60 kHz. Without making a plot of "Q" vs. frequency and analyzing the slope it's hard to say what's causing the resistance.  It may be skin effect, proximity effect, or dielectric losses or some combination of these.
Resonated with Mica caps	Marker shows 94.308 dB at 62.485345 kHz. Ohms = 10 ^ (dB/20) = 51, 927 Ohms. The shunt capacitance is given by: C = 1 / [ L * (2 * PI * F)^2] = 1.34 nF The HP 4332 LCR meter measured the caps at 1.35 nF. The loading capacitance value was chosen so that when the coil, caps and a small variable cap and the input capacitance of an amplifier are connected the resonance point can be brought right on 60.0 kHz. The Q = XL / R = 51,927 / 32.96 = 1,575 A similar plot of just the coil shows that it's self resonance frequency is very close to 500 kHz.  That's good in that you don't want to run a high Q coil near it's self resonant frequency and here we are well away from it.

C-Max

CME8000-Bus-LP-01

CMMR-6P-60

Interference

Graphic displays, both CRT and LCD, emit radiation because of the scanning and modulation signals.  When testing the CMMR-6P-60 using the Rigol scope if the receiver gets too close to the screen the data is totally garbled.

	When the scope is close to the receiver the data is corrupted.
	Moving the receiver away from the scope solves the problem. Note: In a real application if the receiver is near electronic equipment there may be a similar problem. A Nikon D300s camera when close also corrupts the data, discovered when making the video below.

Sensitivity

My first testing with a LED directly connected to the CMMR-6P-60 showed noise during the daytime, but around local midnight the flashing was a solid one pulse per second.  In Oct 2010 with a different CMMR-6P-60 I'm seeing no noise 24/7.  There are two differences, now there's a resistor in series with the LED to limit current (make the battery last longer) and I'm using three AA cells (make the battery last longer).

I notice that the K5JHF clock, just below, did not sync up as soon as it was powered up at 3 pm but did sync around midnight.  It uses two AA batteries and the receiver output drives a micro controller input pin that's very high impedance.  That seems to say the receiver wants to run from about 5 VDC and not from two AA batteries.

K5JHF Clock Kit #7 for the CMMR-6P-60

Kit Assembled Running Without WWVB Receiver	The clock comes up in hh-mm-ss mode and with CW ID active.  The LED flashes along with the CW.

First Letter of Display

L	Loss of detectable signal
U	detected a signal but has not detected a 200ms sync (Un Locked)
E	received noise and is starting the sync detect again
S	detected a 200ms Sync and needs a second sync before it sets the clock
<blank>	two consecutive syncs detected and the clock is set/synced

14 March 2010 DST Problem

The WWVB wall clock is displaying the correct time of 14:34:16, but . . . The K5JHF clock is displaying 13:34:19, i.e. there's a 1 hour error. The Heathkit GC-1000 WWV clock has a similar problem in that it makes the DST/STD time swtich when the station in Colorado changes, not in your time zone. The last sync word is: yy mm dd hh mm ss 10 03 14 05 03 59, so it was in sync early this morning and so the problem is a software bug, not a lack of sync.

25 Oct 2010 - Since the Rigol scope was being used to investigate the CMMR-6P-60 antenna a quick look at the K5JHF clock confirmed that the Pon pin was grounded and to check for digital interference.  If the loop is brought close to the micro controller PCB the data gets garbled.  But when the loop is as far away as the short wires that come with the loop stick antenna the noise is gone.  For most applications seperating the loop stick from any digital electronics by say 6" or more might be a good idea if you don't have a scope to check for interference.

Better Antenna for the CMMR-6P-60

I have some Russian Ferrite rods on the way.  The eBay ad says:
"Large Balun Ferrite Rods 10x200mm"
They are very similar to the 7.5" rod above, but this time I'll make provision to tweak the resonant frequency in a simple manner.

After cutting the tape each rod needs to be cleaned of tape residue.
Rods measure: 9.75 mm (0.383") dia x 199..2mm 7.846" long.

Making coil former from 67 # paper.  Wrapped a little more than one turn then glued and tapped.  Rod slides easily in and out of former now.  The hope is that it will also slide on the rod after the coil is wound on it.  Note that if ordinary 20 # copy paper was used the wire tension would lock it to the rod.

This is about 750 turns of 32 AWG wire.  The former works, i.e. the rod easily slides in and out of the former (O.D. about 0.441")
Luh = (N*N*R*R)/(9*R + 10*H)
N = 750
R = 0.2205"
H = 6.78"
L = 392 uh = 0.392 mh without the ferrite rod inserted.

relative permeability = 25.62 mh / 0.392 mh = 65.4.

Using the HP 4275A LCR meter to measure L and Q while pushing the ferrite rod using vernier calipers gives the following data:
Measured at 40 kHz with 1 ma current in coil.
Note: a Q of 150 is a single count from a Q of 150.

The inductance is very close (R² = 0.9998) to:
Lmh = -0.0169x4 + 0.3405x3 - 1.8206x2 - 1.742x + 25.705

Dist inch	L mh	Q
-0.147	25.58	150
0	25.62	160
0.25	25.37	160
0.5	24.74	150
0.75	23.74	160
1	22.58	150
1.25	21.29	150
1.5	20.01	150
1.75	18.66	150
2	17.31	150
2.25	15.75	50
2.5	14.45	50
2.75	13.12	50
3	11.87	50
3.25	10.62	60
3.5	9.42	60
3.75	8.25	60
4	7.17	60
4.25	6.15	60
4.5	5.2	60
4.75	4.3	50
5	3.556	49
5.25	2.841	43
5.5	2.231	35.5
5.75	1.686	28
6	1.2352	21.1
6.25	0.8902	15.5
6.5	0.6566	9.5
6.75	0.4852	8.6
7	0.4014	7.1
7.25	0.3667	6.5
7.5	0.3615	6.4
7.75	0.3609	6.4

C(resonance) = 1/[L*(2*PI*f)^2] = 1/[25.0*(2*PI*60E3)^2] = 2.81E-13 = 0.281E-12 = 0.281 pf
R(resonance) = (1/Q) * SQRT( L/C) = (1/150) * SQRT(25.62E-3/.281E-12) = 2013 Ohms

Progress

Shown below are the 750, 60 and 120 turn coils.
The 120 T coil has been adjusted to reasonate at 60 kHz with the 4n7 cap..
It would work a little better if turns were removed so it was closer to the center.

750 Turns

This( 750 turns)  is way too much inductance.  It should be more like 1.5 mh (see above)
First cut would be 1.5 mh/ 65.4 = 22.9 uh.

Luh = (N*N*R*R)/(9*R + 10*H)
L = 22.9
R = 0.2205"
H = since L is proportional to N^2  reducing the inductance from 25 mh to 22.9 uh requires a change in turns of 33.
Guess N= 750/33 = 23 then
H = 0.0095 * 23 = 0.216"
Now Luh = (23*23*0.2205*0.2205) / (9*0.2205 + 10* 0.216) = 6.2uh
Another guess:
SQRT(22.9 uh / 6.2 uh) = 1.92 times more turns or 44 turns
N = 44 turns
H = 0.42"
Luh=(44*44 * 0.2205*0.2205) / (9*0.2205 + 10* 0.42) = 15.22 uh
Another guess:
SQRT(22.9 uh / 15.22 uh)* 44 = 54 turns
N = 54
H = 0.513"
Luh = 19.9 uh

60 Turns

OK build:
N = 60
H = 0.570" (former 1" long)
Lwire = 60*PI*0.441 + 12" = about 8 feet
Result:
L = 422 uh &  Q = 63 with coil at center of core.
L = 20.356 uh with air core (a little lower than the target of 22.9 uh) so the target needs to be higher by about 4 times or abut twice the number of turns, so:

120 Turns close spaced

OK build:
N=120 turns
H = 1.14" (former about 2.5 " long)
Lwire = about 16 feet

Result:
Self resonant frequency with ferrite core is about 2.3 Mhz.  i.e. well above 60 kHz.

Dist L mh Q 0 1.264 107.6 .25 1.376 115.1 .50 1.451 120.1 .75 1.524 124.0 1.00 1.581 127.4 1.25 1.625 129.5 1.50 1.6608 129.9 1.75 1.688 130.0 2.00 1.7079 133.0 2.25 1.720 134 2.5 1.726 132 2.75 1.726 132 3.00 1.720 128.8

HP 4274A LCR Meter measuring 160 turn Loop antenna.

It looks like a few turns can be removed to improve the Q at 1.5 mh, but the next step will be to sweep the inductance on the HP 4395A.
After sliding the former/coil to peak at 60 kHz:

Loop 120T close spaced Imaginary no cap	Something may be wrong with this plot
WWVB Loop 120T on Russian Ferrite Real-Z	A 4n7 cap has an impedance of 564 Ohms at 60 kHz.  If the real resistance of the tank at 60 kHz is 37.3 k Ohms then the Q is 66 which is about half the Q from the 4274A LCR meter at 40 kHz.
WWVB Loop 160T on Russian Ferrite Imaginary-Z
	1 Hz RBW Noise is about -146 dBm detection method is sample (i.e I&Q true noise, not peak detection) Tank circuit connected directly to 50 Ohm input. When a Galleon 60 x 10 mm 60 kHz resonant loop-stick was connected to the exact same setup, after 32 averages there is no signal at 60 kHz so the 200x10 mm Russian ferrites make better antennas.

I think the antenna performance metric should be G/T, i.e. the ratio of the Gain to the noise.
C-Max says that too high a Q leads to temperature instability.
The other factor is the impedance at reasonance, i.e. related to the value of the resonating cap.  The cap needs to be larger than the coil's self capacitance in order to get a high Q value, so miniumzing the self capacity of the coil seems like a good thing. 

120 Turns spaced one wire diameter

Maybe try a coil that resonates with the same 4n7 cap but haS
120 spaced turns.
5" former
turns over 2.27" spaced apart. aprox 100 turns.
Measured on 4275A at 40 kHz shows 0.952 mH and Q of 92.
Self resonant frequency with ferrite core is about 4.8 MHz.

Something may be wrong with this plot

131 Turns Spaced Loop WWVB 60 kHz

The photo is named as a 125 Turn loop ( Loop125STcaps.jpg) because the turns had not been counted.  It was in Photoshop that it was determined to be really a 131 Turn coil.

An extension wire was soldered to the above 120T loop antenna and about 30 more turns were wound (to the end of the former.  Then it was measured on the HP 4275A LCR meter showing about 2.4 mH.  Turns were removed until it measured about 1.5 mH with a Q of 235 at 100 kHz.  Then put onto the HP 4395A in Z:Trans mode (RF OUT & A input) with the same 4n7 cap as before and the former moved until resonance was at 60 kHz.  This turns out to be very difficult at this high a Q so a fine tune can be made be tuning a little high then winding on a fractional turn.  Then one wire was opened between the loop and the cap to make a series circuit and that was connected to the 4395A in spectrum analyzer mode (R input).

	Note: This is about the same real impedance as the above close spaced 120Turn loop.  Which is consistent with using the identical 4n7 resonating capacitor and the same 32 AWG wire. 21 Oct 2010 - When soaked in the freezer (zip lock bag) overnight and tested next morning the peak was at 62.5 kHz.  The cap was out of the bag and quickly came to room temp.  Much better to use the C-Max method of using shrink tube to hold the cap next to the ferrite.  Have a bunch of caps of different chemistry on order to see what tempcos are available.
	The same setup as above ("C?" means not calibrated) with the parallel combination of the loop and cap fed from 50 Ohms and driving a 50 Ohm load.  The Q is about: Q = Fcenter / (Fhi - Flow) = 65 where Fhi and Flow are down 3 dB from the peak. But this may not mean much considering the source and load resistances.
	The loop and cap are series connected for this spectrum plot. Taken at 9:30 am 19 Oct 2010 in my office, i.e. near a working computer and during the day.  The signal is WWVB 20 dB above the noise!!! Note the "Smp" means the 4395A is in "Noise" mode, i.e. instead of peak detecting it's actually measuring power by squaring the I signal and squaring the Q signal then adding them and taking the square root To make the noise easier to see the video bandwidth has be lowered to 0.1 Hz rather than use averaging. The improvement may be because of the  series LC connection, the spaced turns covering more of the ferrite or reducing the self capacitance, or something else?

Oct 22, 2010:  Some more of the CMMR-6P-60  WWVB receivers have been received so that a number of receivers can be tested in parallel with different loops.
The first test will be to compare the stock receivers to see how similar they are with the stock loop antennas.
Then replace one of the stock antennas with the 131T antenna and see what difference it makes on the output at different times of the day.  So far the first stock receiver is producing strong output all the time.

Video of stock CMMR-6P-60

The CMMR-6P-60 WWVB Receiver is shown for just over one minute, a full digital data frame and in the background you can hear sharp ticks that are coming from another WWVB receiver.  In another room is a Self Winding Clock Co. "Western Union" pendulum clock that can also be heard.  The red LED is fed through a 4k7 resistor and the receiver is being powered by three Alkaline AA batteries (about 4.5 Volts).

There was a problem making this video in that when the Nikon D300s was close(4" or so) to the CMMR-6P-60 the receiver quit working.  In order to make the video I used a 2X tele extender so that the camera could be about a foot from the receiver.

The data format is at:
http://www.nist.gov/pml/div688/grp40/wwvbtimecode.cfm

Recorded 25 Oct 2010 at about 0913 to 0914 Pacific Daylight Time (1613 to 1614 UTC).
http://www.youtube.com/watch?v=aTuVfS3ix74

Table of Cap Value & Impedance

Skin Depth

Patents

Temic (now C-Max)

Thermal Time Constant

Thermal Conductivity of some materials (Wiki: List of thermal conductivities)

Material	Thermal conductivity (W·m−1·K−1)
Air	0.024 - 0.025 - 0.0262
Expanded polystyrene	0.03-0.033  ((PS Only) 0.1-0.13)

Specific Heat (Wiki: Table of specific heat capacities)

Substance	Phase	Cp J/(g·K)
Air (Sea level, dry, 0 °C)	gas	1.0035
Air (typical room conditionsA)	gas	1.012
Aluminium	solid	0.897

#2 Aluminum Block & Styrofoam Insulation

Block is 6061 3.362" x 2.500" x 2.000" (16.81 cu in or 275.5 cc) and weighs 1 # 12.4 oz (805 grams); 2.92 g/cc or 1.68 oz/cu in.

Styrofoam Insulation is sold by Michael's Arts & Crafts store.   Branded as "Make It: Fun!" for floral arrangements.

B10125WS  1-3/16 x 9-7/8 x 11-7/8 inch (3 x 25 x 30.1 cm Styrofoam Block weight: 2.6 oz (73.7 g) 0.0325 g/cc or 0.0187 oz/cu in.
B181WS      15/16 x 11-15/16 x 17-15/16 inch (2.4 x 30.3 x 45.6 cm) Styrofoam Block weight: 4.2 oz  (119 g) or 0.0359 g/cc
Styro Cutter Model No. 601+ nominal hot Rod ( a hot wire is supported at both ends so can not cut trenches, but a rod can) kerf is 1/16"

The wall wart is rated at 6 VAC & 500 ma for a power of 3 Watts.  This means that it cuts very slowly, not recommended.  The Hot Wire Styrofoam cutters on You-tube are using much more power and cut at a more reasonable rate.  Also it's easy to bend the rod over if you try to cut too fast.

#1510 StyroGlue 4 oz

Looks like Elmer's wood glue.  After one hour still not starting to set.  No info on the bottle about set time.  Some faster way would make doing an assembly much easier.

Notice that the denisty of the Styrofoam is about 90 times lower than Aluminum.

La Crosse WT-3102B WWVB Clock

La Crosse UltrAtomic WWVB Clock (404-1235UA-SS)

This is the newest WWVB La Crosse clock that receives the phase modulation.  I powered it up around noon and within 5 minutes is was synced.

Fig 1

Fig 2 Returned 2020 June 11. For months now pretty much every day at very close to 4:00pm the clock would advance and stop very near 4:00pm. Sometimes is would not make it back to 4:00pm and so would be off by many hours for most of the day. We'll see how the warranty replacement works.

This clock developed the bad habit of running forward at about 4pm, going 12 hours and stopping at about 4pm.  This makes no sense since if it was slow it could just move ahead the few seconds needed.  If is was fast it could just stop for a few seconds. I changed batteries, but the old batteries were not dead. Then it would move forward but not for 12 hours, so now was stopped at the wrong time.  Sent is back to the factory for a warranty replacement.

Replacement Ultratomic clock 25 June 2020

Fig 1 Box as receiver with broken tape

Fig 2 Interesting and good packing.

Fig 3 2:23pm As received: Zone: Pacific Time, DST: On, ECO: Off installed batteries. Clock ran forward to 4 pm. as of 2:54 no movement. 3:35 hour & minute hands move to 3:37 and then second hand starts. Seems OK.

EverSet ES100

This is the chip used in the La Crosse WT-3102 WWVB Clock above that receives the phase modulation signal.

Universal-Solder - EVERSET ES100 -
LINKS and DOWNLOADS

• EverSet Technologies official website
• EverSet ES100 data sheet (PDF)
• Enhanced WWVB Broadcast Format (PDF)
• Download Documentation Package incl. Arduino Code
• AN-002  Energy Consumption
• AN-005 Antenna Considerations
  

Fig 1 SKU: 4260474039982 Close to Fig 9 in the EverSet ES100 data sheet

Fig 2

Fig 3 Advanced Development Kit SKU: 4260474039999 has the IC missing from the Fig 1 version

2013 New Phase Modulation on WWVB

WWVB

WWVB is upgrading their transmission so that receivers on the East coast will be able to synchronize even with a weak RF signal strength by adding phase modulation. The old constant phase (except for the small phase step) is not gone so receivers that locked to the carrier phase, like the HP 114 and a bunch of other frequency standard receivers will no longer work in stock format.  There's talk of a circuit that can be added between in input and receiver that will remove the phase modulation and do that without the degradation in signal to noise ratio that a squaring circuit introduces, but I haven't seen one yet.

Modes:

Mode	Min CNR dB	Rate (bits/second)	Sync (bits)	Frame Period	How Often
Normal	10	1	13	1 min	1 minute
Message	10	1		1 min	infrequent
Fast	30	100		630 ms	10 sec
Medium	-3	1	106	6 min	30 minutes
Long	-13	1	1020	17 min	once per day

La Crosse Model # 404-1235UA-SS - makes use of the new phase modulation WWVB signal "UltrAtomic Time" - Leapsecond.com - see WT-3102 above

http://www.nist.gov/pml/div688/grp40/wwvb.cfm is the NIST web page talking about the new phase modulation format.
http://www.nist.gov/pml/div688/grp40/upload/NIST-Enhanced-WWVB-Broadcast-Format-1_01-2013-11-06.pdf is the paper, but does not cover all the different formats.

WWVB Time signal Broadcast: An Enhanced Broadcast Format and Multi-Mode Receiver, Liang, Eliezer, Rajan & Lowe, IEEE Communications mag. May 2014.
This paper goes into some detail about the different frame length messages.  There are a number of references with links.

New NIST Time Code to Boost Reception for Radio-Controlled Clocks -
Information on Time and Frequency Services - suitable for NTP
JJY - The Method of Emitting Standard Time and Frequency Signal Emission -
MSF Radio Time Signal

SMU - Yingsi Liang - publications (9 Aug 2014)

• Y. Liang, D. Rajan, O. Eliezer, “Receiver Design of Radio-Controlled Clocks Based On The New WWVB Broadcast Format,” IEEE Trans. Wireless Communications, accepted for publication.
• Y. Liang, O. Eliezer, D. Rajan, and J. Lowe, “WWVB Time Signal Broadcast: An Enhanced Broadcast Format and Multi-Mode Receiver,” IEEE Communications Magazine, vol. 52, no. 5, pp. 210–217, May 2014.
• Y. Liang, O. Eliezer, D. Rajan, A. Ramasami, W. Khalil, “Interference-Robustness Improvement in BPSK Receivers for the Enhanced WWVB Broadcast” in IEEE Texas Symposium on Wireless and Microwave Circuits and Systems, April, 2014.
• Y. Liang, D. Rajan, O. Eliezer, S. Balasubramanian, and W. Khalil, "A New Broadcast Format and Receiver Architecture for Radio Controlled Clocks," in IEEE International Midwest Symposium on Circuits and Systems, pp. 1128 - 1131, August 2013.
• Y. Liang, H. Liu, and D. Rajan, “Optimal Placement and Configuration of Roadside Units in Vehicular Networks,” in IEEE Vehicular Technology Conference, pp. 1–6, May 2012.
• Y. Liang, O. Eliezer, and D. Rajan, “Optimization of Cosine Modulated Filter Bank for Narrowband RFI,” in IEEE GLOBECOM, pp. 1-5, December 2011.
• O. Eliezer, T. Jung, R. Lobo, M. Appel, Y. Liang, D. Robbins, and P. Nelsen, “A Multi-Mode Software-Defined CMOS BPSK Receiver SoC for the Newly Enhanced WWVB Atomic Clock Broadcast,” in IEEE Radio Frequency Integrated Circuits, June 2014.
• J. Lowe, M. Deutch, G. Nelson, D. Sutton, W. Yates, and P. Hansen, O. Eliezer, T. Jung, S. Morrison, Y. Liang, D. Rajan, et al. “New Improved System for WWVB  Broadcast," in 43rd Annual PTTI Meeting, 2011.
• Y. Liang, D. Rajan, O. Eliezer, “Sequential Frame Synchronization based on Hypothesis Testing with Unknown CSI,” Manuscript in preparation.
• Y. Liang, D. Rajan, O. Eliezer, “Design of Non-linear Block Codes Given Unequal A-priori Message Probability,” Manuscript in preparation.
• Y. Liang, D. Rajan, O. Eliezer, “Design of Sync Word Given Unequal Energy per Bit,” Manuscript in preparation.

Patents

Many of these have some amount of duplication.
8270465 Timing and time information extraction from a phase modulated signal in a radio controlled clock receiver, Oren E. Eliezer, Xtendwave LLC , 2012-09-18, Patent Citations (55) (1965 - 2010) -
8331201 Leap second and daylight saving time correction for use in a radio controlled clock receiver, Oren E. Eliezer, Xw Llc, Grindstone Capital, Llc, Xw Llc Dba Xtendwave, Dec 11, 2012, 368/47, 375/329, 375/316, 368/28 - "The one second/one hour corrections are scheduled to occur when they should take place and the correction is applied exactly when DST or leap second is to go into effect, without having to receive anything around the time of the correction."
8605778 - Adaptive radio controlled clock employing different modes of operation for different applications and scenarios
8659457 Self-compensating digital-to-analog converter and methods of calibration and operation thereof, Oren E. Eliezer, Ryan Lobo, Mark Appel, Xw, Llc., Feb 25, 2014, 341/120 Not clock related           
8774317 - System and Method for Phase Modulation Over a Pulse Width Modulated/Amplitude Modulated Signal for Use in a Radio Controlled Clock Receiver  - Phase Modulation
20130121399 - Timing and Time Information Extraction in a Radio Controlled Clock Receiver -
                        8300687 of the same name but issued Oct 2012?
20130051184 Real-time clock integrated circuit with time code receiver, method of operation thereof and devices incorporating the same, Oren Eliezer, Thomas Jung, Steve Morrison, Mary Cooley, Xtendwave LLC ,

G04R20/08 Setting the time according to the time information carried or implied by the radio signal the radio signal being broadcast from a long-wave call sign, e.g. DCF77, JJY40, JJY60, MSF60 or WWVB -Citations (1987 - 2004)
20120082008 Low Power Radio Controlled Clock Incorporating Independent Timing Corrections, Oren E. Eliezer, Aditya Awasthi, Xtendwave LLC, 2013-09-10, H04W56/0035 Synchronisation arrangements detecting errors in frequency or phase -  Patent Citations (57) (1965 - 2011)-

List of patents by Xw Li

DCF77

The phase modulation system is similar to the one used on the German DCF77 time station, so a receiver that works for it might be modified to work with WWVB.  

Elector magazine for Jan 2002 has an article by Steve Marchant of the UK on a DIY DCF77 receiver.  Marvell Consultants -  DCF77
Blikenlight - The Clock - by Udo Klein in Germany a DCF77 receiver shield for Arduino. The hardware front end is a commercial module (the larger the loopstick the better).

MAS6180C receiver IC

Micro Analog Systems Oy is making what appears to be a family of time code receiver modules similar to the C-max (MAS6180C.pdf).  In addition they offer a family of time code test equipment.
I've asked if their RC-88 signal generator has both AM and phase modulation in the WWVB mode.
Universal Solder - CANADUINO 60kHz Atomic Clock Receiver Module V3 WWVB MSF JJY60 (MAS6180 based) -
The new version includes 74HC14 buffering of the inputs and outputs as well as a ME6209 (pdf) 3.3V regulator

 older version of MAS6180 from 2016 (this was a raw 6180  on a PCB)

Patents

RF Interference

I've had a couple of encounters with RFI recently in regard to WWVB receivers.

The first was in relation to the La Crosse UltrAtomic wall clock.  The factory replaced it 25 June 2020 because at 4:00 pm every day it would go crazy.  After that in November 2021 I got a Starlink 2-way satellite system that comes with a router.  Because for each the past five years there has been a wildfire within a few miles of my house (Oct2017 & scroll down from there) I have multiple Internet Service Providers (Wiki: ISP) since none of them has all the attributes I want (Reliable, Fast, Low cost).  So I now have three ISPs and three WiFi routers (Wiki).

2.4 Ghz WiFi Band from Agilent E4404B Spectrum Analyzer

AT&T/D-Link router 5 to 7 squares from the left. WISP router 4 to 5 squares from the left Starlink router 1 to 2 squares from the left.

All three of these routers are within 15 feet of the UltrAtomic wall clock.  My guess is that they are causing the problems.  I plan to get a ladder and move the clock far from the routers and see if it starts telling time.  Since the arrival of Starlink it has NEVER told the correct time. The clock stopped working and I thought it needed batteries, but getting stuff moved to make room for a ladder caused me to just ignore the clock.  Every now and then the hands moved, but that seemed like a weak battery symptom. 

...the second RFI case.....  A friend received a La Crosse S84107 Wireless Forecast Station that includes a WWVB receiver.  When first installed it did not synchronize to WWVB on neither an East-West axis nor on a North-South axis.  The same table held chargers for an iPhone and iPad as well as a couple of cordless phones.  When all of those were moved over ten feet away the S84107 gets a solid signal.  I have not tried to figure out which is the problem but note that both the iPad and iPhone contain Wifi transceivers that often emit signals even when they are in standby mode.  I think cordless phones only emit signals when in use, so my guess is that the WiFi is the problem with both La Crosse devices.

Note that RFI (Wiki) is usually associated with what's called "in band" signals, i.e. when the interfering signals are in the same band as the device receiving the interference.  In this WWVB case the interfering signals are at a very different microwave frequencies but are causing the WWVB receivers to malfunction.  This has been a problem for as long as there have been radio receivers.  The better receivers have filtering that rejects most if not all out of band signals.  But modern receivers are designed with front ends that accept everything and these designs are susceptible to out of band interference.  The WWVB problem may not be just the front end but could be anywhere since microwave signals could get into any part of the receiver and cause problems.

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